I don't use a color wheel but have found the packs of cropping blocks invaluable! Lets you take lots of colors, often many shades and layer them in different ways without drowning in big sheets of paper/card stock.
Since most photos are 4x6 (or smaller once cropped) they work most of the time. If I have enlargements or know I'm going to be doing an extended layout once I select my colors I can take the cards to LSS and select the larger pieces. LSS carries them in plastic cases (which are archival and reusable for scraps!) and I saw them last Friday at Hobby Lobby in bound form.
Deb
P.S. DH bought me an Ott-lite for my b-day in January and I've found it to be incredibly helpful in the color selection process. Really brings the colors out in the photos and helps see subtle differences in the papers!