Of course, by all means, ask for extra time off. They'll be happy to accomodate your needs. Go ahead and ask for three or four weeks vacation, and be sure to let them know you'll be using every last minute of personal time off you're allowed. They love it when potential employees ask these questions. They like their employees to be tanned and rested so they will return to work ready to drive business, besides that, you deserve it. Don't forget to let them know you got plenty of vacation at your last job, and that anything less than that will make you unhappy and disgruntled. They'll understand. If you have kids, be sure to let them know you'll need to take some time off when they get sick or have school functions. Heck, you'll probably be able to negotiate more time off than the person interviewing you! While you're at it, ask for a higher car allowance, it will show you have great negotiating skills. Why not ask for a higher mileage reimbursement, too? They'll be glad to give it to you if you just ask for it.
If you do these things you're going to be a shoo-in for this job, it's practically yours already! They are going to absolutely love you. Picture yourself on the podium accepting the "Rep of theYear" award because you are sure to win it.
Good luck, fellow new co-worker, and....good selling!