As far as servers that have connected servers attached to them, there are advantages and disadvantages. One huge advantage is the fact that every server your primary server is connected to effectively gives you 11 additional character slots, which is really nice for extreme altoholics. A disadvantage is that you take a latency hit from having connected servers. When US-Ner'zhul was connected with two other servers (that were about half its population combined), I immediately starting getting a 30-50 ms latency increase over where it was before the connection, and over what I get on other non connected servers on the same data center.
One thing to consider with PvP servers is that even if you choose one of the 95%+ faction dominated PvP servers like Illidan, Mal'ganis, Kel'thuzad, etc, you are still subject to CRZ in all zones outside of Pandaria. That means that when you are leveling (1-85 zones), the faction domination isn't there, and you are subject to ganking from other servers. Even PvP servers where world PvP in max level zones is non existent can have a pretty irritating leveling experience. If you want a PvE server because you don't want to be bothered by world PvP, don't choose even a 99% dominated PvP server unless you never level alts.
I wouldn't worry about time zone; time zones are kind of fluid across servers. For example, Stormrage (EST server) has several late night guilds on it. EST guilds often raid on PST servers. Not only that, but whenever a realm connection goes into place, the server's time zone is actually subject to change. Ner'zhul was a PST server but became a CST server because of realm connection somehow. I'd more worry about data center and getting somewhere that has low ping.
http://www.wowwiki.com/US_realm_list_by_datacenter
If you're in eastern Canada, you'll want a NYC datacenter server ideally. Central Canada probably a Chicago server, and western Canada, probably LA or Phoenix. Your ping can easily go from 20 ms to 150 ms depending on which data center server you're on; I know mine does (on the east coast of Canada).