I have used the travel department six times over the past three years. I have found them very good. We also wanted to go to Dubrovnik but checked out first if we could do it any cheaper ourselves. By booking our flight and hotel ourselves we were able to do it for considerably cheaper. When in Dubrovnik we sussed out the hotel that the travel department use and found it somewhat away from the old town but still in a nice quiet location. The city tour is nothing, you can do this yourself. Medjugore? Yeah we thought so too! We didn't do the Elphite Islands but went to Cavtat by boat ourselves. Easy to do.
One thing when travelling with the travel department that you are required to do is to share a table in the evening with the same people from day one. We found this particularly bad on our last trip to Tuscany/Rome (Last May) as the couple we were sharing with had awful table manners of the picking teeth/nose/ears variety.
My suggestion would be to do Dubrovnik yourself (Aer Lingus) and stay for 4 days maximum, you will see everything. Use the travel department for more out of the way places.