I would like a grand hotel that adds to food and drink ratings (internal restaurant) as well as bigger capacity. It can have 4 pathway connections so we can have more fun with placement. I agree we need either new buildings, reskins or mirror images. One idea I had was a convention center that brings more people in and has a plaza attached. Multiple pathway connections.
As for the limited space on islands, I look at it this way- if you want people to visit all the islands you have species only found on each island. So I like to make sandbox islands with species only found on them. I don't view a island as, well, a island. I view it as one part of a huge park that spans multiple islands. Sandbox also allows you to make smaller enclosures without making Dinosaurs mad.
The small island sizes don't bother me and It shouldn't deter the development of more decorations and buildings- it gives a chance to make our islands more unique.