I never had one - and it was in my birth plan that I was not to have one unless it was absolutely medically necessary, and not just out of medical curiosity or routine. Internals increase risk, so if you don't need one, don't let them do it. Find out in which situations you would be expected to have an internal, so that if someone suggests it during crunch time, you have the foreknowledge not to be flustered about it and just say no if it doesn't fit into a 'medically necessary' scenario...and word up your birth partner!
Have a great time and enjoy your birth experience!! I did