Neenah you can find online or at Xpedx stores.
Prism Simply Smooth you can find at many LSS. Bazzil's new Coconut Cream cardstock is good also.
Gina K and Papertrey Ink are both great papers.
As for stamps to color in, there are soooo many out there!
(I am biased, but you can always get Our Craft Lounge
Stamps, as I draw all my images to be colored in with Copics AND I show an example with the stamp of how you can color it
Otherwise, you can try AMuse stamps for really small, fine images, Flourishes for classic elegance, Papertrey for clean / modern designs, Cornish Heritage for licenced images and fun designs, Crafty Secrets for vintage/retro, Our Craft lounge has cute but slightly quirky art and a healthy mix of other styles... each company has it's own flavor so you need to find a feel you like.
That's the beauty of market variety. So many ways to branch out beyond SU!