We were in Tanzania in late August. This is actually winter in Tanzania, but since it is so close to the equator, this doesn't matter that much. In most of the parks, it was in the high 70's to low 80's (fahrenheit) during the day and would cool down to the low to mid 60's in the evening. Ngorongoro Crater Lodge was the one exception, where it would get down to the high 40's at night. Since we were there during the dry season, the humidity was fairly low. It was sunny every day in the morning, but we'd often have clouds (sometimes thick) in the afternoon. It was clear almost every evening, providing an absolutely spectacular night sky. I have never seen the Milky Way galaxy so vividly.
Mosquitoes were almost non-existent. There were a few on our first day in the village of Muhala, but we didn't see (or feel) any more for the rest of the trip. The Tsetse flies, could be a bit of a pest though. There were a few places, particularly in the Serengeti, where these were a nuisance. 20% DEET insect repellant seemed to work well against these as well. The Tsetse fly bite is similar to a mosquito, although it doesn't itch as much. The obvious concern, though, is catching some kind of disease from the bites, so I used repellant on the two or three days when these were a problem. We saw very few other bugs while we were there.
I should note though that Tanzania was having a serious drought when we were there and even some of the rivers which normally flow in the dry season were nothing more than a few mud puddles. This could account for a lower bug population than normal.
Dust was probably the most annoying aspect of our safari. On the drive between Tarangire and Ngorongoro Crater, the heavy red clay dust got into everything. Everyone would scurry to roll up the windows whenever a car was coming the other direction, but it was still suffocating at times. The dust in the parks wasn't as bad since we were all driving very slowly. Still, when a gust of wind came up in Ngorongoro Crater, we rushed to get our camera equipment inside plastic bags.
The food was a lot better than I was expecting. The lodges went out of their way to accommodate our desires, even handling the vegetarian needs of Diana's sister and her family. In some of the lodges, (Crater Lodge, Kirawira Lodge) the food was as good as you'd expect in an expensive restaurant in a major US city. Serengeti Serena Lodge served the food buffet style with a large range of choices. I think the worst food we had was at the first lodge we stayed at - Ngare Sero - but even this was quite acceptable.
On a few occasions, we had box lunches prepared by the lodge we stayed at the previous night. These were generally fairly good, but there is no provision in the trucks to keep the food cold. My intestines became a little upset after eating a sandwich with mayo in the first box lunch we had. After that, I was very careful what I ate in these lunches.
Most of the lodges we stayed at provided some laundry service, although it would often take 24 hours or longer to get the laundry returned. This meant that we could use the service once at each lodge. All of us had shirts and pants purchased from Travel Smith or REI which are designed to dry very quickly. On most evenings, we rinsed our shirts and pants in the bathroom sink and they were dry the next morning. If you use this kind of clothing, you can get by with three shirts and three pairs of pants fairly easily. Underwear and socks took a lot longer to dry, so having more of these was helpful.
As mentioned above, the safari shirts and pants worked great. The pants with zip off legs were particularly useful on the hotter days, although I only felt the need to take off the pant legs on two of the days we were there. I wore hiking boots most days, although the only time I really needed these over sneakers or sandals was when we were hiking in Mahale. If you're not including this in your itinerary, you could easily get away with just sneakers. A warm jacket (polartec is probably adequate) for Ngorongoro is almost a necessity. We also brought rain ponchos but never used them.
I think there may be only one paved road in Tanzania and we didn't spend much time on it. The dirt roads we used when traveling between parks aren't really that rough, but the constant vibration can be a little aggravating. The roads in the parks (and the road to Treetops) can be considerably rougher, but you're usually going much slower on these roads so it's not a significant problem. By far the worst aspect of the non-paved roads is the dust.
With the exception of Mahale camp, the bathrooms in the lodges were all what you'd expect to find in an American hotel. In fact, the bathroom in our Crater Lodge room was probably one of the most impressive bathrooms I've seen. Even the Kirawira tented lodge had very nice tile and wood bathrooms.
The Mahale camp is a temporary camp which is rebuilt ever year (actually twice a year I believe). It has no plumbing but we didn't feel we were really "roughing it." A deep pit toilet with a wood toilet seat is provided behind each tent. Hot water and a warm shower are provided whenever we asked by heating the water over a fire. The warm shower consisted of a bucket held in the air with a rope with a sprinkler head mounted on the bottom. You could also use the lake, of course, which was comfortably warm and very refreshing in the middle of the day.
Between lodges, however, the bathrooms were not particularly welcoming. For us males, this wasn't really a problem, but by the end of the trip my wife and daughter missed good plumbing more than anything else.
We were asked to limit our luggage to a single 15" diameter by 30" duffel per person, plus a day bag. This proved to be more than enough space. In fact, on the way back, we consolidated most of our luggage into two duffels for the four of us, and used one additional one for the souvenirs we purchased (padded with some of our extra clothing).
We purchased four large nylon duffels from Lands End which met the dimension requirements - all four in bright yellow with our name monogrammed on the side. This made it very easy to keep track of our bags through baggage claim and as they were carried around the lodges by porters.
We had no problem with lost or delayed bags, although our stopover in Amsterdam on the way to Africa probably avoided any of the typical baggage routing problems. To make sure we wouldn't have a problem we divided our clothing, toiletries, etc, between the four bags so that even if one went missing, we wouldn't have a serious problem.
We carried all our camera gear with us on the planes (see Photographing on Safari) and also had a day pack with binoculars, first aid, toiletries, extra underwear, etc.