Im pretty sure most would be only too happy to spend 30 mins on top of you.
And I totally get what you're after. My maximum is 1 full hour of face sitting and it was totally wonderful. She started by saying no tongue and wearing her panties (fine by me - I love the taste of moist cotton) but by the end she was panty free and dripping as she had her third orgasm.
At the end she said that it was one of her best experiences - and one we have repeated many times.