If you really want to maximize, stay onsite only as many nights as needed. Unless of course rates are pretty similar.
You can stay very close offsite for about $100-120/night. Onsite often $220 and up.
If you stay onsite one night, you get to use the express line both days of your stay - so stay Saturday night, use the pass Sat and Sun. Changing rooms is nuisance, but the savings can be well worth it.
I was there a month ago and stayed offsite on a Friday, hit the RPR hotel first thing Saturday, checked in and left our bags (room happened to be ready) and hit the park with hotel key in hand. Hit the park first thing Sunday for some rides and about 16 consecutive rides on Bluto's barges, went back to change and check out of the room around noon and then headed back for the rest of the day.
Checked into a different hotel Sunday night and visited the park Monday afternoon after a conference I was at was done.
Total for the 2 nights offsite was less than the one night onsite. We did more rides than most people probably do in a week!