I think buses will be used to begin with but I can see a lot of problems rising from it, mainly traffic and insurance if an accident were to happen.
A monorail seems like the best choice for several reasons.
1) It avoids traffic and allows Universal more control over the travel times.
2) If the track is raised, the windows can potentially be blocked out. I'm not saying create something similar to HE but anything would be better than looking at the hotels and some of eye sores on I Drive.
3) I think a few people have mentioned that when Universal Blvd was built, it was built with the intention of a monorail being added at a later date, hence the wide median for most of the road. (Speculation on my part but there could already be plans there for it since Universal previously owned this land) Looking at it on a map, I do see some trouble spots in crossing Sand Lake Road and I4 into the resort.
4) Depending on how many stops it makes between resorts (If any besides the Wet n Wild plot) there could be a potential for external funding.
5) They have high capacity
6) They're essentially giant bill boards travelling between the resorts.
As an idea, I've added the MK monorail station and added it next to the RP car park. I think this would allow enough space for the track to loop back around onto Universal Blvd. I think the station is close enough to CityWalk for guests to walk via the existing walkways from the hotels (Obviously this will have to be widened) For any of the guests staying at the hotels, a boat stop could also be added.