I think that the bugaboo over caramel and crystal malts has been overstated. I see them mostly in IPA's, but I can tolerate them in other styles, such as an amber. Oddly, for my standard Helles recipe, I use a little Goldswaen Carahell (around 5-6%) and it works out pretty well with an IBU to balance at around 18 IBU's. Others may stick with a Munich or Vienna addition to the pils base as the "other than pils" malts...try it out and choose what tastes best.
Cheers!