You'll hear many different opinions on that question, and so here is mine:
1) as many people already pointed out, you only need a ticket (which will also grant you a badge and a con book, wherein you'll find a map and program of all things happening) to enter all points of interest. Lobby, bar and restaurants are open to anyone, as they're being operated publicly by the hotel. Strictly said, if you "only want to drop by after work and meet a few furries", you don't need a ticket.
2) Chat up with a few attending furries beforehand and make some friends that you already know you'll meet there. Jumping into the cold water and hoping to get in touch with someone, especially when you're not the approaching kind of person, can leave you with a stranded feeling when everyone around have their groups.