I travelled with Thomson Safaris in 2008. Did the luxury lodge tour through the northern circuit (Serengeti, Ngorongoro Crater, Tarangire).
Thomson Safaris is one of the biggest operators in Tanzania. They are US based so you do all your coordination with the office in Boston. It certainly makes it easy and comfortable for a first time safari goer as they're easy to reach and chat to about any questions you might have. Their big, fancy operation also has something to do with why they're so expensive, I'm sure
In Tanzania I found them quite organized, though my luggage didn't arrive on our inbound flight and wasn't found until the day we departed! Make sure to split your clothes between yours and your wife's bag!
My #1 tip, if photography is a priority for you, is to arrange a private vehicle/guide. Spend the money to get that done. The last thing you want on the trip of a lifetime is to be stuck in a vehicle with people you don't know who have a different set of priorities.
Good luck booking, and enjoy! I went back to Kenya after having such a great time in Tanzania and I'm officially a safari addict. It's the greatest adventure.