I would definitely do two paddocks so you can rotate; it's a huge help.
Other things to consider - how much time your horses spend out on pasture, and what you do about manure will greatly influence the quality of your pasture.
If you're planning on keeping them in stalls part of the day, you'll have much less wear and tear. Keeping them off the pasture when it's really wet is also an excellent suggestion.
If you pick the manure piles up or drag or harrow your paddocks you'll have more even growth and fewer dead spots.
I usually drag the old paddock as soon as I move the horses into the other.