The Photographer's Ephemeris is a great software package to get started with these sorts of calculations. There is a free desktop version that you can use at home before your trip, and if it turns out to be really helpful, there are paid versions available for iOS and Android.

This tool lets you mark a spot on a map and then calculate sunrise, sunset, moonrise, and moonset for any day you choose. The vectors of these events are shown as colored rays on the map, and the times and moon-phase are shown, as well. As the question indicates, sunrise and sunset calculations depend, among other things, on elevation, and TPE can help with this. The mapping tools are aware of elevation, and based on various entries in the release notes, it appears that altitude is accounted for in its calculations.

Per some of the comments on this and others' answers, though, another factor is at work in practical instances -- the obscured horizon. In the simplest case, you'll have an unobscured view of the horizon:

In practice, however, very few of the really interesting landscapes feature perfectly flat horizons, so we'd ideally like to take into account the elevation and distance of those obstructions, as well:

Although TPE (to the best of my knowledge) won't account for all of the objects that might obscure the horizon for you, it does have some features that might help to an extent. There's an ability to set a secondary location on the map and compute the distance, bearing, apparent altitude change, and elevation change to that location. So long as you know that this is where your apparent horizon really is, you can plug this elevation back into TPE, which will calculate its effect on events.

As you can see, there's a bit of a knack to really getting the most out of TPE, but there are some great tutorials that walk you through scenarios like this.

• clipart from http://www.free-clipart-pictures.net and http://all-free-download.com/free-vector/photographer.html