My wife and I are going to Portugal for 8 nights later this month. Currently planning 3 nights in Porto and then traveling by train to Lisbon for 5 nights. My question is whether I should book one night in Coimbra and only stay in Lisbon for 4 nights. Alternatively, should I make Coimbra a stop on the way to Lisbon or not go at all?

Thank you

I like Coimbra, but I suppose you could see the university library and the Roman ruins at Conimbriga in one day. Not sure what you would do with your luggage.

Yes, luggage storage in Coimbra is a little challenge - there is no official storage at either train station. You might ask at one of the hotels directly at the little station (Coimbra, not Coimbra-B) and ask if you can leave your bags there for a while. Otherwise, google for info. I'm sure you can work something out.

It's a nice little town but small. It is a nice break from the touristy Porto and the super-touristy Lisbon, though (and hotels, while not especially nice, are cheap, for what it's worth). I spent two nights in May on the way between Lisbon and Porto with a day trip to Nazare (by bus). I wasn't interested in seeing any more Roman ruins so didn't see the ruins near Coimbra.

Consider taking one of the regional trains from Porto Campanhã station that goes directly to Coimbra and doesn't need to change at Coimbra-B instead of one of the high speed trains. Even though regional trains stop more often, you probably make up the time saved in speed by avoiding the layover at Coimbra-B. I took both regional and IC trains in that region and found the regional trains more comfortable, just because they were less crowded, and I could spread out.