Every pregnancy and every labor is different, of course, but just because you're having multiples doesn't mean you'll have double the pain. If it helps any, look at this way: You're getting off a little easy — multiple babies for the price of just one labor!
As for the actual delivery, the likelihood of having a c-section greatly increases with each additional baby, but many twins are born vaginally. In this scenario, you're going to have to push twice — once for each baby — and there will likely be about 15 to 20 minutes in between the two births. So after baby number one arrives, you'll have to muster some additional strength and keep in mind that hey, you're not done yet!
If you're having more than two babies though, you should definitely prepare for a c-section. But as long as there are no complications, the process will be very similar to a singleton c-section.