Yes, Ljubljana would make a nice base for western Slovenia, which is where most tourists focus their sightseeing. If you're the type who wants to avoid changing hotels and have one base, Ljubljana would be nice for that. The trains don't go everywhere but Slovenia does have a good bus system. You might consider a few nights in Piran on the coast - beautiful town. I loved Ljubljana also but it is small.
Bled makes a good base if you want to spend a few days exploring nearby Lake Bohinj etc. If you just want to see Lake Bled, you can easily just day trip in from Ljubljana.
Most tourists seem to see western Slovenia but I enjoyed visiting Maribor and Ptuj as well in the eastern part of the country. You can day trip to Ptuj (a beautiful little old town) by bus or train from Ljubljana I think (I stayed over in Maribor.). Another really nice small town closer to Ljubljana is Škofja Loka, which I think you can get to by bus. (I had a car by then.)