On the insides of cards, LOL, I don't stamp mine either until I am ready to send it on, then gear inside towards the recipient if I can. Gilbert still looks at the inside too, that s what got me laughing.
On stamp sets, I find I am going back a lot to my SU stamps. I just found LaLaLand crafts and I love their images for coloring. Also yumi and Fumi but I haven't purchased any from them yet it is a BIG want. I did purchase a digi from LaLaLand and have used it several times already. I like the few Ginak I have purchased or won they stamp beautifully and I like the simple clean style of the stamps she offers.