I think the "two" is the operative word. Couple posters above only had one. One kid is cool you can focus entirely on them and do the parent hand off thing to keep one fresh.
Two kids changes things and skews the dynamic. We rarely traveled anywhere without our first for the first 4 years. Add in a second and Mommy & Daddy need some recovery time!
My kids are 5 years apart. I remember going to Myrtle Beach in 1996 with my first daughter. We spent the entire time worrying about her being too hot, too much sun, getting chilled in the air conditioning, getting sand in her eyes/mouth, bugs getting on her, crying in restaurants, changing diapers when there's no facilities on a beach...it was more stressful than staying home. 1st time parents are especially going to freak out because they're over-attentive. Expect to be staying in your room watching TV a lot due to baby-things.
The 2nd one coming along 5 years later was actually not as bad but not relaxing either.
The best time to take kids on vacation is when they're between the ages of 5 and 12. They get discounts on food and attractions, they're generally happy that they're out to somewhere new, and they like to play so you get a kick out of them having fun.
Before 5, they're too much maintenance and you spend most of your energy tending to them rather than enjoying yourself. They cry or need something every 3 minutes.
After 12, they start "getting bored" with everything, and you hear about it CONSTANTLY. Driving sucks, airports suck, beaches are boring, there's nothing to do, I don't like any of the food around here, etc etc. In their teens, they think vacations are actually "shopping trips" and want money every 5 minutes.
And that, my friends, is parenthood