Because Y2K is a relatively short route, you can easily combine it with another route. Luckily for you, there are many classic climbs only 10-15 minutes away. Most of these classics are at a slightly lower grade, but still good fun.

The closest route is Dark Shadows (5.8) which is only a few hundred yards North of Y2K. Dark Shadows climbs an amazing varnished corner in a very scenic setting. If you haven't ticked it off yet, you should definitely go for it. The climb can be very busy, so your best bet is to climb Y2K first, and hope the line for Dark Shadows is gone by then.

At a lower grade, you could go for Birdland (5.7+) or Rawlpindi (5.7). Both are great climbs on the left side of the Brass wall. However, these two climbs can make for a killer full day by combining them together, so it would almost be a pity to do one of them after or before Y2K. The Brass Wall also has many great single pitch routes, which can be climbed to fill your day.

The Southern end of the Mescalito buttress is home to Cat in the Hat (5.6) and Cookie Monster (5.7). Cat in the Hat is the most climbed classic of its grade in Red Rocks, so it can be busy. You can avoid the potential crowds at the start by climbing Cookie Monster, which ascends an amazing corner filled with jugs and huecos. From the top of Cookie Monster keep going up the upper, and best pitches of Cat in the Hat.