Hope this is helpful even though it's a little disorganized! Please don't hesitate to ask questions. If you'd like to read my blog (with pix!), I'd be happy to send you the link. Also, I haven't proofread this, so please forgive any typos and poor grammar. :)
METRO / TAXI: On arrival at SOF, I took the Metro into town. Step outside the airport, look to your left, and there’s a building with a big “M” logo on it just a few steps away. Enter the building and at the bottom of the short ramp there’s a ticket machine. The fare is 1 lev, and the machine gives change. There’s a snack stand in the area, and the barriers to the trains are to the right. There happened to be a train waiting when I went through the barrier so I rushed to get on. (Needn’t have done, as it sat there for another five minutes or so.) The car was roomy and clean, and I didn’t feel that my suitcase was cluttering up the aisle. The ride to the Kliment Ohridski (Sofia University) stop took maybe 20 minutes; I never felt unsafe or nervous.
At the end of the tour, I had to take a taxi back to SOF. (The Metro doesn’t open till 5:30 a.m., and I needed to be at the airport by 5:15.) Receptionist at the Hotel Crystal Palace organized the taxi the night before; that early in the morning with very little traffic, the journey took around 12 minutes and cost 12 leva.
SOFIA AIRPORT: Must admit that I didn’t take much notice on arrival. All I remember is that there was some sort of blockage at Customs, and people started hollering about it. Also, the guys in Lost Luggage were helpful – though ultimately unsuccessful – when I discovered that my suitcase had been opened by TSA and re-secured with seriously heavy-duty cable ties. I asked if they had something that might cut through the ties; the scissors they produced didn’t stand a chance. (I ended up asking the guy who ran the snack stand mentioned above: he brought out something similar to a box cutter and managed to saw through the ties. Seriously, TSA, how do you expect the average traveler to get through those ties?)
Departing from SOF seemed a little chaotic but it went quicker than it looked like it would. At that time of the morning virtually none of the restaurants and shops were open, but it looked like all the usual stuff you see in airports. Nothing special.
GETTING AROUND GENERALLY: It was easy to get around all of the cities and towns we stayed in. Sofia is big but I found it to be walkable, and there’s always the Metro if you get tired. Plovdiv and Veliko Tarnovo were hilly but manageable. Watch your step no matter where you are: sidewalks have loose or broken stones and there are little “potholes” everywhere. Varna’s newly renovated pedestrian area was a particular pleasure because I didn’t need to worry about twisting an ankle.
WEATHER: The first half of September was gorgeous and often very, very hot (at least for this Seattleite). It’s not the heat though, it’s the humidity! I wished I had brought a few lighter-weight shirts and a second pair of capris not made of denim. Live and learn. If you bring sandals, make sure they’re sturdy ones (see sidewalk comment above).
MOSQUES: We visited the mosque in Sofia as a group, and there was an opportunity to visit the Friday Mosque in Plovdiv on our own. Women must be prepared to cover their heads, and everyone must remove their shoes. I brought along a big scarf to cover my head/neck, as did several other women. One woman, however, forgot to bring a scarf so she pulled her cardigan up over her head and buttoned it under her chin, which was totally acceptable. Our guide said a hoodie would work just fine too. As long as your hair is covered, you’re good. (Note: At the synagogue we visited, men were required to cover their heads. A basketful of yarmulkes was available in the foyer for the men to use.)