Did you ever play a COG or HG game, work hard to romance that girl or guy, and then leave feeling a little unsatisfied with how vague the culmination of that romance was portrayed? I think there are some games that could be reworked and released as hearts choice games. You have the PG version on HG or COG, and the spiced up version on hearts. I know writing that sort of material may not be particular authors cup of tea, but a partnership with someone who does well with that, and maybe not so well with the general fiction side could render spectacular results.
I think ZE safe haven would be good, the lost heir saga too. Flesh out the sex scenes, add in a few more, perhaps add some polyamory for variety. Safe haven in particular would really suit the Eric Vall treatment. Not familiar with the author? Look up some of his books. That is a real popular genre right now, there are a lot of authors doing that stuff, and plenty of people consuming it. That style is begging for the choice treatment.
Just a thought.