SuperShuttle is reliable and inexpensive that's for sure!. However, here's my experience with SS out of LAX. We got into the van and about 1 1/2 to 2 hours later we arrived at DLR! There were three other "couples" in the van and they were going to their residences and we were the last to be dropped off. So, basically, we spent 2 hours driving around the suburbs of LA trying to find addresses and get people home. It was a long morning that's for sure!
So, if you don't think you want to be stuck in a van with strangers all getting a ride home from LAX, you might want to try getting a private car instead.
I will never do SS again. I'll get a private car, limo, taxi, etc. and splurge a little bit.
If you are staying at a DL Resort Hotel, I'd do the Disney Bus that takes you directly to the hotels.