How and why do you use your HP calc?

[JimP]

Why do I use my HP calculator? (Which might at any one time be a Prime, 17bII+, WP34s, 50g, or 35s) Because fiddling my way through sin(29) = (as one has to do, say, on a TI-89 Titanium) is annoying beyond belief when all I want to do is press 29 SIN. Because entering a calculation where you do anything other than X enter Y [operator] is counter-intuitive to the point of self-inflicted baldness.

How do I use my HPs? With a great deal of appreciation. Daily, without actually spending as much time as I could, digesting all their capabilities. But I'd rather have a good HP (or, say, a DM or WP) than any of the other major brands.....