13 Jun 2010 at 16:53 - 3
I'd recommend buying new character slots until you have 1 of each class (for PvE) and at least 1 PvP slot. If you really hate playing a specific class (or more than 1) than that reduces the number, but 11 is the 'safe' number to have 1 PvE character of each class and 1 PvP character.
But as noted above, additional campaigns add 2 slots, so buy the other titles for more classes, more storage, more skills, more PvE content, etc. and when you own all 4 titles, then buy the character slots. An extra account works, but I rarely use my second account as it is easier to do things all on one. Hero builds are easier by having skills unlocked, and unlocking skills for 10 classes is easier when you have those 10 classes to buy skills with. It also is a hassle to transfer items from one account to another unless you have 2 computers to run both accounts at the same time, or use the GWx2 program to run both on one computer.