If you had the choice would you do a 7-night
disney cruise or spend 8-days at WDW with a 4-6 month old baby?
Which cruise line? Most of them won't allow an infant to board until they're 6-months-old, and some require them to be a year.
DCL is 6 months.
Personally, I would opt for the 8 days at WDW. I made numerous trips to WDW with my daughter when she was an infant and they were fantastic trips. Babies require a lot of gear when traveling and it's much easier finding space for all of it in a hotel room compared to a stateroom. Infants/toddlers are also free at WDW until they turn 3.
Cruising can be a little challenging with infants. Depending on which stateroom category you book, your room can be small and finding space to store baby gear can be difficult (a car seat and stroller can take up a good bit of space in a stateroom). Space for a pack 'n play or crib is something to consider, as is the fact that there's no real way to separate the baby's sleeping area from the rest of the room (more important for those that wake easily to sound/light). A huge plus, though, is that DCL has bathtubs in their bathrooms, most lines do not offer that convenience. Cost-wise, on DCL, infants are not free -- they sail at half the cost of the child fare. Also a plus, the nursery is beautiful.
DCL is great, but I don't think I would have brought my daughter on a cruise that young. She was a very light sleeper (until 5!) and I found it easier to work around that in a hotel room. She also loved the sights and sounds of WDW, and while DCL has a lot to offer, it just could not provide what the parks did.
