Might start with a search here for RY4 Double..... That should get ya started.
Black Honey Tobacco is another thats somewhat popular, Tho I get no Honey or Tobacco from it..... its different !
PLENTY of variations on the RY4D mixes should be able to keep ya busy for awhile.
I mix RY4D @ 6% 14mg 50/50 PG/VG a couple hundred mls at a time, steep for a week minimum, and use it as a base for several recipes.