I have premium membership. The different levels of membership and what you get for them are detailed on the website, but from memory the biggest advantage is that if the sitter cancels at short notice or has to leave early, then I'm covered for costs incurred getting a paid sitter or for a cattery.
You also get free use of an airport lounge twice a year - I've never used an airport lounge before, but am taking advantage of this in February as I'm taking two flights to get my destination then.
There has been a bit of upset over the past couple of weeks as Trusted Housesitters has introduced a confirmation fee (£9) paid by both sitter and pet owner at the time of booking. This doesn't apply if you have Premium membership, but it was introduced without any prior discussion or warning, and people are very annoyed about that. That said, some people have looked at alternative pet sitting websites, and reckon that THS still is the best one. There's a FB group where all of this has been shouted about discussed.
Have a look at the website and see what level of membership works best for you. It's always worked well for me. I do a video call beforehand with the sitters to get a sense of who they are, and look for those with lots of good reviews.
I don't provide food, although I usually leave about £20 in case they need to buy more Dreamies!
I've never considered them having parties, but sitters are usually from somewhere far away, and don't know anyone locally.
And I just leave the house clean and tidy - no special cleaning needed.