You can try Sam's Club for the next 3 mos. for only $10. A good way to see if it works for you. Personally, I got rid of my Sam's membership because the lines were always so long there. Very annoying.
Currently have BJ's and Costco and like them both. Costco is great for pre-made fresh meals, Kirkland diapers, etc. Warehouses overlap on many items (so I buy when convenient of have a coupon). BJ's is handy for milk, Uno's pizza, birthday cakes (when you don't want the huge Cosctco sheet cake), Pediasure, etc. So much of warehouse shopping is YMMV---if you can, go with a friend who has a membership and see what works best for you. GL!