>>1164148>Specifically I would like to string a 3 day hike in some intermediate terrain (nothing to difficult, as gf is going to join this time) with great scenery and not too much elevation gain.Frankly, if you've got mountaineering experience you're good to go for anything in Romania. I can't think of any notable mountain ranges that are technically difficult, at least during the season; some of them demand a high level of fitness though. I'd avoid the Fagaras since it's too big to cover in three days. The Bucegi and Retezat, also very scenic, are smaller and more suited for a 3-day hike. The Eastern Carpathians are extremely obscure and offer little in the way of hiking infrastructure like maps, trails, shelters etc. The only exception would be the the Ceahlau, which is touristically fairly well developed. It's small and very compact and would be good for a comfy hike if three days is all you've got but I imagine the climbs to be tough too.
The Apuseni are less alpine but still stunning. They're less accessible than the Southern Carpathians but way more than the Eastern Carpathians. Virtually unknown among international travellers but I assure you they are very scenic. I'm not sure about shelters and huts but there are lots of trails and enough settlements that you should be able to find a place to spend the night if you don't want to camp. The climbs are also way more moderate; some of the villages on the Southern slope are located at 1300m altitude. The Southern area, known as Tara Motilor, is very scenic by itself.
Keep in mind that the huts close as the season approaches its end, though that varies from hut to hut.
