I like trading games. I cut my teeth on Elite, waaaaay back in the day. I loved that game, and it's bug-ridden sequel Frontier.
Differences: Port Royale includes the ability to build stuff and expand towns etc. East India is limited to the actual trading side of things. Both are good games in their own right, I enjoyed EIC quite a lot for a while. Ultimately, with the absence of town expansion, the hook of the game lets go after a while.
PR2 however, is a fun game, but it's aged REALLY badly, and is locked in pre-widescreen resolution.
An alternative to PR2 would be Patrician 4 - Better graphics, similar game. The main difference is that it's set in Europe, but you can build up towns, buy them out even, run huge fleets of ships. It has pirates and random events too, and you can end up owning entire cities and corner trade markets if you play it right.
The latest version of P4 is also multiplayer co-op, which can be interesting. Me and a mate stuck some hours in the other night, it got a bit frustrating with him constantly buying everything and leaving us penniless, but it was stuff fun nonetheless.
I'll be getting PR3 though, once it drops a little in price. It promises full multi-player too, which should make things interesting.