Why don't you try Marris Otter, Golden Promise or Halycon for a slightly more flavorfull premium base malt? Munich and Vienna are great choices too, but for me, Vienna has a very pronounced bready flavor, not much on the maltiness.
I would try and add all your ammarilo late in the boil to really let the aroma and flavor shine. IBU in the 35-40 is plenty sufficient. The thought of a Golden Promise, Amarillo SMASH makes my mouth water.