Welcome to the Dis!!!
You have listed some wonderful options! Here are my thoughts:
With an 8 month old baby, convenience is critical so I would focus on the resorts that get me where I want to go in the easiest, least disturbing to baby, manner possible. Of your choices I would be inclined to stay at the CR as first choice and the BC as second. The monorail or walking are the easiest ways to get around WDW with a stroller, IMO. There is no other resort as convenient to the MK as the CR - especially when you have a stroller to maneuver. A TPV tower room will give you a huge room with a terrific view from a spacious balcony. You can relax out there in the evening and during afternoon naps while baby is asleep. It is a beautiful place to relax and enjoy the spectacular view and evening fireworks. Request a high floor for the quietest room.
The main drawbacks at the CR are the basic pool area and the small elevator that you will need to take to get to the monorail level. Although, TBH, you will need to take an elevator to get to the monorail at the Poly or the GF as well, but these elevators are a bit distant from the monorail so don't feel as problematic somehow. The pool, although plain, has lovely views over the lake, and has always been peaceful when we stayed at the CR, especially relative to the Poly volcano pool which can get 'busy'. Also noteworthy: To go from the CR to Epcot you need to change monorail lines at the TTC. You might want to consider the Poly if you plan to visit Epcot often as you can walk from there to the Epcot monorail, thus avoiding the change at the TTC. The main problem with the Poly is the risk of no balcony - that would be a huge issue with a napping baby, IMO.
BC is in a great area, as you know, for Epcot and DHS. The problem here is the bus to the MK. If you plan on visiting the MK more often now baby is here, using the bus with a stroller is a bit cumbersome because you have to fold and unfold it every time you use the bus. Another issue is room size. You mentioned wanting extra space, but the rooms at BC are significantly smaller than the rooms in the MK resorts. Personally, I believe that you would still be able to manage, but there is less room. Then the balconies at the BC come in full size and tiny "Juliet" balconies with only enough room for one person to stand out there. Not a useful relaxing place for Mom and Dad to enjoy a glass of wine or a coffee while baby is sleeping. IMHO, you would really enjoy this balcony space when baby is asleep (and you are not), so any risk of paying deluxe and not getting a balcony would be a deal breaker for me. If you want the Epcot area and have already stayed at the BWI, I would suggest the YC over the BC. It is also at the end of Storm Along Bay with the sandy toddler shallow area. (It's a slightly longer walk to Epcot but only by a few minutes.)
I wouldn't do a Kidani villa simply because you would have to bus everywhere. Save for a later visit, IMO. But if you really want a separate bedroom and living area, this would be the choice that provides the living area you want in a peaceful setting.
AoA looks fun but would better work when baby is a bit older, IMO. There will be a lot of stimulation in the theme parks for your little one. A more relaxing place to rest and sleep would be the better choice for 'home' for an eight month old, IMO. AoA is a value resort and, while these are fun, they can be busy and offer less refuge from the hustle and bustle that pervades much of WDW.
Enjoy planning your trip!!!
Well, we had a great trip and found it was NOT difficult using the buses. So, transportation, for us, is not a big deal.
