heya,
sounds a wonderful size tank, yoyo loaches are little white and black loaches like a clown but white and black instead of orange and black, sadly clown's loose there colour as they get older and just turn into a dark grey colour. where as the yoyo loaches remain the same just get lazier, i got 3 personally in one tank and their like best mates, its so cute like a parties of girls going out on a friday night.
snails are brillant i use them in my smaller growing on tanks to mop up food if any is spilt. but for this i use apple snails BTW. not related but do not under estimate snails, but they do breed like crazy! upto 300 a time! every month!.
the snails mentioned above for eating snails are often rare in uk shops, and you can pay upto £10 a snail! in some places.
hope this helps.