I fly first class frequently, though not exclusively. The service is excellent, since the flight attendant to passenger ratio is so much better. Drink service starts on the ground, and food and beverage service starts almost immediately after takeoff, within a couple of minutes.
I've flown first class is many aircraft and on many routes. The planes would include F-100, MD-80, 727, 737, 757, 767, DC-10, and MD-11. I think that's all of them. I've flown first on at least the following routes, probably others: SAN-ORD, SAN-DFW, SAN-JFK, SAN-LAX, LAX-JFK, LAX-ORD, LAX-DFW, DFW-ORD, DFW-BDL, ORD-BDL, ORD-SWF, ORD-LGA, DFW-LGA, SNA-DFW, DFW-IAD, ORD-DCA, ORD-HPN. That's all I can think of. You can see that most of my travels take me to the east coast
As for food and seats, it depends largely on the aircraft and route. The intercontinental aircraft (767, DC-10, MD-11) have a much nicer Premium First cabin (at least on American). The seats on these planes have 60" pitch, full sleeper recline, and electronic footrests. They are quite wide and very comfortable. I have not yet experienced American's new Premium First product, but I expect good things from it. The food is excellent in first class, but on Flagship Service routes (SAN-JFK, LAX-JFK, others I haven't flown on), the food is magnificent. The dinner menu on American's Premium First is usually six-eight courses, with several appetizer choices, three entree choices, and a lot of good food. Dinner service on these flights can easily take two hours or so. You can see an AA dinner menu
on my website. It's from a JFK-SAN flight.
On smaller planes, first class is also nice, but not as great. The food service is excellent, but not as abundant due to shorter stage lengths. The seats are also smaller, and the pitch is significantly smaller. As a general rule of thumb, I am willing to pay the (non-rev) upgrade fee for all daytime (meal) flights, and some overnight flights. When I take a red-eye, I usually decide whether to upgrade based on how full the main cabin is going to be. Sometimes I also consider whether I'm hungry, because first class gets food on the SAN-ORD red-eye, while the main cabin passengers just get pretzels and soda.
I personally really enjoy sitting in one of the premium cabins, and to me it is very worth the price. The price, however, is a lot less than for most people as I non-rev with an employee discount. I'd be quite reluctant to spring for first class if I were a full fare passenger!