When you say "play" diapers does that mean you will not use them (wet/mess) or does it mean behind closed doors, can be thick because your not wearing outside of the house?
If you want thick & thirsty:
Abu Space/Littlepaws/simple:
http://www.abuniverse.com/
Dc Amor or Idyl
Bambino (Bellissimo = thickest):
http://bambinodiapers.com/
Rearz (Safari are thickest):
http://rearz.ca/index.php?cPath=85&osCsid=42amnciol7bdv1vk1r2458dhv6
Not so thick (or I have not tried):
Tykables are very cute & fit/feel amazing but on the thin side & not as absorbent (still a good choice for little time)
Barebums (cute print, I have not tried them yet):
http://www.barebumdiapers.com/
Awwsocute (Great fit & quallity but pricey):
http://www.awwsocute.com/
Check out various diapers (samples):
http://www.wearingclouds.com/
My personal favorite so far for wearing at home only are the ABU Space diapers. They are really thick so it's hard not to waddle when you walk, have a very high capacity and swell alot! The tapes are better than any diaper I've ever tried and can be refastened several times. The whole diapers construction is high quallity and the entire ABU team are all ABDL. The Rearz safari diapers look like an amazing choice but they are so exspensive to ship into the US. I have tried the spoiled by Rearz and they are a great diaper but the DC diapers are very similar at a cheaper price. The one thing I don't like about the DC diapers is the feel of the plastic outer shell, other than that, great diaper. My number one out and about diaper is Bambino Bellissimo (or Teddy) because of it's quallity construction and high capacity, also a good "staying in" choice.