Hi there Stephanie,
This is a great question. Unfortunately, Trulia does not have this feature at the moment, but I can still help you get the same results with a little bit of extra work.
Finding the best route between a list of destinations is actually a long standing mathematical problem called The Traveling Salesman Problem, or TSP for short. (If you're curious, you can read more about it here: http://en.wikipedia.org/wiki/Travelling_salesman_problem
There are TSP solvers online, and one in particular that uses Google Maps. That's what we're going to use to do exactly what you're talking about here in your question. Just follow these steps:
1. Go to http://gebweb.net/optimap/.
2. Click " Bulk add by address or (lat, lng)" (it's on the left in blue)
3. In the white textbox that appears underneath, first type your home address or whichever address you will be starting your trip from. (This assumes that you will want to do a round trip back home after you're done visiting houses. If you're not returning home, just skip this step.)
4. Underneath your starting address, now add the addresses of all of the homes you wish to visit. (Be sure to include all the details for all addresses; street number, street name, city, state)
4. Click the "Add List of Locations" button below the white textbox. You should now see all of your addresses plotted on the map to the right.
5. Click the "Calculate Fastest Roundtrip" button.
6. Click "Export" (above the "Calculate Fastest Roundtrip" button)
7. In the dropdown from "Export", click "View in Google Maps"
This will now open up the fastest route to all of the homes you're interested in, starting and ending at your home, which you can save to your maps with your Google Account.
I hope that helps, but feel free to reach out to me if you have any further problems.
Community Manager (and math guy)