Well, when I want extra heat I just add salsa to what you have listed. Maybe try cream of mushroom soup instead of the milk. I like to make some guacamole and put it out separate from the queso along with sour cream and salsa. Just let people mix it up in their own bowl however they like.
Second what Kwisatz said. Cream of mushroom for a little different take.
Instead of milk, use evaporated milk, it maintains the consistency a little better.
Your favorite salsa is always a nice touch.
Blue velveeta-more expensive but better.
fresh jalapeno's, cilantro, purple onion, and tomato - definitely!
Chili Fixin's by Rotel - hard to find but so good.
avacado
i usually get a jar of pickled japs and pour some of the juice into the mix, sounds weird but it makes it spicier and everyone has told me it is unbelievable.
ended up just browing the sirloin with hatch chilis...then added Central market pico de gallo...turned out pretty good...but the pico is a little to tart from central market...next time i will just make my own
Yeah, I have tried pre-made Pico in queso and it just does not taste right. Take the extra time to get fresh tomatoes, onions,a nd jalapenos from the produce section. It makes a WORLD of difference. You can get a little chopper and do the onion and jalapeno and all you have to cut up is the tomato. I have the Best Queso at Super Bowl parties every year and it does not take that much longer than opening a can of Rotel.