The climb up 49 will be tough to see a lot as the road is quite winding with a good amount of tree cover, so you'll see the riders come around a bend and back through another bend. This is dependent on where they place the KOM point. Also, the road is pretty narrow with minimal shoulder and only a few turnouts, so you'd have to get up there early and likely be there until the road is reopened. With that...it is a steep climb and a KOM climb, so if you want to see guys hurting, that'd be a good spot.
Alternatively, the climb up Indian Hill is relatively flat with an open view of the road, so that might not be a bad vantage point. Not as steep and not a KOM point though.
The sprint through Auburn would also be cool.
Something else to consider would be selecting your foothill viewpoint such that you can get back to Sac to see the finish. If you're out on 49, that may be tough.