US Envoy is very similar to the Cathay biz seat, and is probably the best US-based biz seat out there right now, at least until AA make the new version of it widely available on its fleet.
The biggest issue I have with US is you're forced to connect through PHL or Charlotte, which cuts the length of a TATL flight considerably (essentially breaks the trip in half from the West Coast), especially annoying when flying overnight as you lose a lot of potential sleep time when you compare with flights over 4500 miles.
F is standard US F, so seats like a slightly nicer PE VS seat, but not by much; flights over 2000 miles get proper meal service (so SF-PHL would get a proper meal) short flights on US get somewhat funky service (would probably not be an issue on short connections from PHL or CLT to Florida, you will have had two meals on MAN-PHL and will just want to sleep). US is inhabiting this twilight zone between a low cost and a full service international airline, and seems to be happy doing so. I've mostly used them on east coast shuttle flights as they have good presence in the BOS-NY-PHL-DCA space, and their very strong presence in both LGA and DCA makes them ideal for jetting about into NY and DC.
1-stop flights are also known as direct flights, and connections are usually timed pretty well; if you check flight status for the flight number it will usually show you the two separate flights and you can see the detailed timings, or just do a search for MAN-PHL, then PHL-MCO to see the details of the individual flights. I'm going to guess the connection time is going to be in the order of two hours. More like 45mins to 1:30 on the return from SF. Lounges in PHL aren't likely to be much of a factor as a result, you won't have much time to spend there.