I flew TA from SFO to KTM last year. Very pleasant experience. New plane, good service, nice leg room and great food (alcohol included). Coming back I had about 25 hours transit. TA gives you free hotel and shuttle but you need to get visa (see below). Also the hotel had free dinner and breakfast which was great. If you have any questions contact them directly via Facebook messenger. They were very good at replying back.
You need to get visa from Turkish Airlines office (not embassy) located near Jai Nepal Cinema hall (visa fee is about $50 per person I think). I'm not sure about the process to get visa from USA though.