Based on availability, my budget and booking.com scores, I've narrowed my choices in Porto to these:
1. Being Porto Hostel, Rua de Belomonte 13. Large private room, en suite.
2. Porto Belo Clerigos, Rua de Sá de Noronha, 41 . 1 bedroom flat with a washing machine (yay!!) and a terrace
The prices are so similar, that's not a factor. The flat looks and sounds more comfortable, but the hostel looks to be in a better location. From what I gleaned, the flat has A/C, the hostel doesn't. I'll be there in late May and while I don't expect it to be hot, I often find that closing the windows and turning on the AC makes for a much quieter night. If there's no big difference in location, I'd choose the flat, but location is really the most important factor for me.
I'd also like recommendations for rooms in Tomar (I'll have a car) and in Aveiro and Coimbra (no car). I'm hoping to pay about €70 tops. Most important for me: good bed, modern bathroom, shower, AC, location and clean.