7-8 hour car ride

Nautical2012

DH and are plan to take a babymoon at Atlantic City, but it's about a 7 hour drive from Boston.  I forgot to ask at my dr's appt yesterday about taking such a long drive. 

I'm due July 16, and we haven't decided if we are going to go in March or May. Do you think there is any benefit to going sooner than later with such a far away trip?

Also, I am prepared to make sure I'm hydrated, and take frequent breaks to stretch, and I'll do my leg exercises to help prevent clots...

Would you go in March or May if you were due in July?  Or do you think it would it be better or worse to take a 3 hour flight to Florida?