Doesn't matter where you stay, JW or Casa--they're connected. Our preference, and return trips are always to Casa- much more beautiful/convenient lobby, walkways and mezanine areas. Easy access to JW pools, where your girls (ours are same ages) will meet others. Best shopping, Louis Vuitton, Tiffany's, Dolce/Gabbana are a short bus trip away. Once in the area, there are TONS of shopping options. Senor Frog's, Hard Rock, Aqua clubs many others. NO, I would not want my daughters to go and stay til the wee hours ALONE
I am late in answering this....but the Club 91 "feature" is WELL worth it (Similar to Tradewinds in Aruba and Cloud Club in Arizona) but don't EVER think you can get it for free. If you consume alcohol it is absolutely worth the 150 a night they charge or whatever it is now...I am not sure if kids are allowed there....many have changed the policy on the children. For me, I am glad they have limited children's access as it is really an "upscale" experience....not an "all inclusive". I would thinnk the Casa Magna would be better for kids....but thats just me.