Spent some time there in 2005, summer trip, no problem with weather or snow in the hills. Crossed from Villach in Austria, (nice place) through Kranjska Gora turned off the main roads through Triglav National Park and Radovna down to Bled. Nice route, some easy non-metalled roads, wonderful scenery and Bled was a lovely place. Rowing out to the church on the island in the lake rather than using the powered trips was warmer than it looked. As you go over to the North East past Mirabor it takes on more of the feel of old Eastern Bloc rural peasant land. Back into Ljubljana, nice city, bars and restaurants etc Bit of a bike meet on Wednesday nights at one of the bridges, (cant remember the name, main touristy one!) plenty of variety in bikes and a chance to meet and talk sh1t with other bikers.
Route down to the Slovenian coast has good roads, though a lot of roadworks interupt the flow. Postojna has the Castle set into the cliff face which is impressive. Get past Koper, the industrial docks area and the coastal area has some interesting spots, no real beaches though apart from the private ones linked to hotels etc. It is easy to get across to Croatia from there where the coast line is much better. Also along the Croatian border there are quite a few abandoned villages with loose surafce roads which are worth visiting.
Found it all very cheap, friendly and overall a great time. Will go back again.