As others have said, get decent padded shorts. I find DHB are fine for me and at the opposite end of the price spectrum Assos fit great as well.
Riding on the turbo is hard work as you don’t really get the constant change in sitting/standing/moving around that you do out on the road. I’m quite happy with 6 or 7 hour rides out on the road but have only just done my first turbo session that was over an hour long.
Make sure that your bike fits would also be a good thing to look at, if you aren’t sat on the saddle correctly then no amount of quality padding is going to help. Basically you want pressure on your sit bones (clue in the name) rather than your plums or perineum.