I have stayed at both and love both! Our last trip was in late March into early April, we did 11 nights at CBR. It was a PERFECT stay. We hadn't stayed there since 2006 and it was so nice to be back. Our room was spotless and we didn't find it to be dated (it does only have the double beds however) at all. It had been updated since our stay in December of 2006 and while I "hear" its next on the refurb list, to us the room was in great shape and very clean. The grounds at CBR are gorgeous, we loved all the beaches with the lounge chairs and hammocks (each village has its own beach) and dh and I really enjoyed having a cocktail on the beach and watching the high fireworks of Illuminations a couple of times. I think the pool would be ideal for your kids. It has zero entry, a few slides and a gated off height restricted (I think both of your kids would be fine on that unless the 7 year old is very tall) pirate splash area. We had fine bussing, it is large and unlike the Poly you have multiple stops. However you do not share with any other resorts. DHS and Epcot are extremely close and given its central location, MK, AK, DTD and the waterparks are not far either. We really enjoy having multiple quiet pools, we went during spring break and on more than one occasion we had the quiet pool in Jamaica to ourselves. I like the way each village has a bus stop, quiet pool and laundry right there. Again, its spread out but you have amenities nearby regardless of section (this goes for CSR too) and while its large, we find the resort very easy to get around and don't mind a bit of walking. You can always pay for preferred which puts your right at the main area.
Now all that said, we are trying CSR next trip. We haven't stayed there since 2006 either and we can't wait. Dh, dd and I went over there last trip and were impressed with Pepper Market and had forgotten how lovely the grounds are. I like the three distinct themes CSR buildings have and the fact it has queen beds. It has the most dining options of any moderate (including room service) as well as an athletic club, spa and salon. The main pool is very large and it has a very long slide which is great for my teenagers (they were 9 and 11 last trip and still remember that slide).We also loved the quiet pools there last stay and I know we'll enjoy them again in October.
I don't think you can make a bad choice. They both have a beach/tropical type feel. I think you'll really enjoy having a food court (really miss that when we stay deluxe or
DVC) and the pool areas at both are in my opinion superior to the Poly's (but no stellar view of the castle

). They also both have nice pool bars and CSR actually has a pool bar, the Laguna Bar which is near the food court as well as a nightclub/bar.
We have had great bussing at both (and at POR and POFQ for that matter) and while you can't walk to a resort, and its not on the monorail, we find that bussing works fine. In fact I prefer the transportation at the mods, because I cannot stand the shared bus routs of the monorail and Epcot resorts.
Good luck with your decision!