Judy does have a good point.
Here is the tips compilation.
No, staying onsite is nowhere near as important as it is at WDW. Onsite guests can take the monorail into Tomorrowland in the opening hour, but unless you're staying at DLH and would walk by the monorail station anyway, that honor is a bit dubious in my opinion (mainly b/c each time we tried it while staying at PPH the monorail was closed, and each time we did it while staying at DLH, the line was so long that we would have done better, timewise, to just walk!). Onsite guests can have purchases sent back to Bell Services at their resort, available for pickup the following morning. Onsite guests can charge back to their room. Onsite guests get access to the Magic Morning during their stay, not just the one allowed with tickets of 3 or more days.
But in terms of being closeby, yesterday I was playing around on mapmyrun.com, and noticed that the walk from the Tropicana, one of the closest offsite motels, to the center of the Esplanade (the big area right between DL and DCA) is .29 mile, while walking from the place where DLH meet DownTown Disney to the same spot in the Esplanade is closing in on half a mile. The walk from GCH is about the same as Tropicana to that Esplanade spot, BUT that doesn't include the walk from your room (which during our stay made it the same distance as though we were walking from HoJo's parking lot).
Seaworld is good, especially if you take the time ot see the Pets Rule show! We LOVE that show. My brother, who has the same personality that the character Michael Westen from Burn Notice has, loves that show b/c he loves their kitties.

Brother and my sister in law bought annual passes to Seaworld simply so they could go see that show at will (they live in San Diego). They've been known to meet for lunch there!
I haven't found big discounts on SW passes, but if you thought you'd want to go for two days, I often see "2 for 1" tickets on seaworld's website. That gives you the chance to see all the shows you want to see AND wander around to visit the Clydesdales, penguins, etc etc without rushing.
What it comes down to is that you don't have to have a 4 or 5 star hotel trip, in order to have a GREAT trip.