We had one crib which both shared for the first six months, with me getting up to rotate them as needed for nighttime nursing. It was a good choice for us, since they had all the room they needed at that size and since I was so desperately ill, co-sleeping would have been a very unsafe option.
FWIW, at 6 months, I had regained enough of my health to make co-sleeping a viable choice, and we got a California King bed, some guard rails, and joined the king to a single and we haven't looked back.
I think it's good, actually, to have a couple of options available to you - you never know what you will actually use most. We had two cribs but ended up happier using just one for both girls. We also had a bassinet but that really didn't hold both of them. I never tried the co-sleeper, but I can imagine it would save you getting up to walk across the room to get them.
Some families "sidecar" the crib to the side of the bed, so that the crib itself works as a co-sleeper. It takes a little mechanical maneuvering, but it can be done.
Congrats on your pregnancy!