[saluki]

I would only give the typical notice, 2 weeks here.

I've given more notice to try to be a team player and it gets awkward being the 'short timer' for more than a couple weeks.

Definitely agree to get all your stuff out of the office before giving your notice, just in case.

Don't feel like you should give them more notice, even if you're friends with them, two weeks notice is what they are expecting.

On a side note I'd try to have a new job lined up even if you negotiate a start date a month or two out for some time off. Easier to find a job when you have one is the rule.

Good luck leaving and starting your new adventure.