...but camping has its attractions too, and not just the price.
I guess that if you feel you can read a map, do some internet research, talk to locals and want to spend time on that sort of thing, then why not go DIY. Especially if you dont want to ride with a big group, or want to ride at your own pace, stop when you want, etc
Or, if you just want to ride, and/or are a trail centre type person, have your food cooked for you, then guided is probably best.
I've done both, just saying that you shouldnt rule either out (as these threads tend to turn into Classifieds on STW).
Sorry - none of this answers your question about red-graded-like trail locations. Most of the Alps bike parks will have what you need - groomed DH and xc type stuff, particularly in the tree line. You could look somewhere like Andorra if you wanted to avoid the Alps, but a bit tougher to get to.