I expect the Springs would be most convenient as you will be close to the food court, shop, pool and bus stop. Our DD has used the pool there at 16 months and more recently at 27 months. She loves it and we think it is the best pool for her. The Donald splash pad, little water slide and zero entry make it brilliant for pre-schoolers.
I dont think it will be a problem for you wherever you stay but The Springs would involve less walking for his little legs.
Actually, the rule of thumb is count in months up until 36 months. That's when they grow from toddlers to preschoolers.
I would also recommend the Springs. We just got back from a stay in a Grand Villa at SSR. We were in the Springs and we loved it, my 18 month old and my four year old *loved* the pool, we ran to the carriage house several times, and it was only a quick walk over the bridge to the playground. Our view was overlooking one of the lakes that all ducks congregated in, and we fed the ducks every day.
We are also hoping to go back in Oct/November 2007 and hope to stay in a Grand Villa again and hope to be in the Springs again...maybe we'll see you there!
As for "toddler" and "30 months", being a grandmother, I don't know if in the UK we use the word "pre-schoolers" - I'm not really into the jargon! "30 months" was easier than putting in "2 and one half",