Soarin', the Mailiboomer, and Grizzly River have single rider also, though during cooler weather GRR sometimes doesn't offer it. At DL Splash has it all the time and Indy has it sometimes (depends on whether they have any passes or not, which they never seem to anymore.
I've read on another board that Indy no longer has single rider line/passes.
I also read that the single rider line is sometimes longer than the fast pass/stand by line for Soaring. ( keep an eye on line length here)