J_Darnley: Right thanks for all your input.
Then it isn't worthwhile building them until you have the couple million that you need to build a fully working one.
Well depends on what you mean by "fully working one". You won't get access to the casino room type for a while (IIRC), and even with that it tends to be more effective to create multiple smaller hotels rather than one massive one. The reason being that tourists do their thing in a room/location, then tend to leave that location and go for a wander until they find the next "fun activity". If you have multiple smaller hotels, they can (in theory) just bounce between them.
By which I mean, one hub and a wing is probably enough for most hotels (especially the first island since space is more of a premium). I don't think a hub + all three wings is ever actually necessary.
It didn't stop me from building one massive hotel anyway (just because I could) - hey if I'm going to end the world I want an impressive hotel. You know, for evil functions, evil conferences, evil seminars, evil workshops, and most importantly, evil poker tournaments. But it just took up space and cost money to be honest.
One final thing: I've probably mentioned this elsewhere, but you may notice that the number of hotel guests your island has is correlated to how many hotel rooms you have! So the more hotel rooms you build, the more guests your island will have! But somehow, there will ALWAYS be SOME tourists on your island, even with no rooms built at all (which you've no doubt noticed). So it looks like you can't win...
However, I like to think that having lots of tourists (from various different countries) enhances the "deception" or the "facade" of the evil base. Unfortunately as far as I can tell it appears to make no difference whatsoever, but I still like to think that. I also like to think that agents will be less likely to shoot to kill if there are civilians around, but that too is probably not true (especially where Rambo is concerned) - although the tourists will absorb some of the agent's bullets, and you get more corpses for certain things if you like that sort of thing, so there's an up side... ;)