DW & I stayed at Clarion Suites Lisbon, based on positive reviews at
tripadvisor. We were very pleased. For less than the price of most hotels, you get a suite, consisting of a bedroom plus a combination living room/dining room/kitchen. It was clean and well managed. The only riff on this place, noted in the tripadvisor reviews, is that it's a little (not a lot) out of the way. But it's about 3 blocks from the subway, which is then a direct shot into the tourist area. Better yet, the walk from here to the tourist district is about 20 minutes, slightly downhill, and through interesting shop and tourist areas itself, and past several very nice parks. If you stay here, I'd recommend that you do as we did -- take the 20 minute walk to the tourist areas, spend the day, then take the subway or one of the very inexpensive cabs to get back to the hotel.
I highly recommend it. Other than location, it's ideal.
(Note to self -- I still haven't done a tripadvisor review for this).