Salema has been ruined by over development, but it certainly won’t be quiet in July, which is peak season. Many places are already fully booked, so your issue is more likely to be finding suitable accommodation. Salema is quiet in the winter months.
With only 8 nights in Portugal, the Algarve, being the most developed and touristy would be the area I would drop if you want to see more of the unspoilt Portugal.
If you haven’t been to Portugal previously, I would suggest 5 nights in Lisbon including day trips to Sintra and Cascais and 3 nights in Porto to include the Douro Valley. Evora is also an interesting place to visit as a long day trip from Lisbon or an overnight stay.
There are plenty of good beaches between Lisbon and Porto including Foz do Arelha and
Sao Martinho do Porto. Personally, I don’t care for Nazare.