I can only do one night in either of the two. If it's Lucerne, I'll have lunch in Lugano and arrive in Lucerne at around 4pm and I'll have to check out at 11am the following morning. I'd it's Lugano, I'd arrive around 1pm and check out the next morning at 11am and have lunch in Lucerne on my way too Lauterbrunnen. Any ideas?
I love Lugano because it is like a little bit of Italy in Switzerland. If it is not a Sunday night, my vote is to stay overnight in Lugano, have lunch in Lucerne and then on to Lauterbrunnen. Evenings are fun in Lugano. You did not say if you were driving or taking public transportation but I am thinking it is easier to get to Lauterbrunnen from Lucerne.
There are plenty of possibilities. I would skip Lugano, in order to arrive earlier in Lucerne. That way you could take a wonderful excursion on the lake boat, connecting to cable car or cog-wheel train to the summit of Mt Rigi. It's about 1 1/2 hours from Lucerne to the summit. I found the details on the transportation pieces on page 105 of our Switzerland guidebook.
I did lunch in Lugano and 2 nights in Lucerne, and I really enjoyed that. Lucerne is beautiful, great for walking around, and has nice options for lake or mountain excursions. I liked Lugano and really liked Lucerne, but then I only spent a few hours in Lugano. I think you would do well with either, but I would recommend Lucerne.
I would skip Lugano and go to Lucerne, then maximize time in Lauterbrunnen.
I agree with the previous reply. With such a very short time frame, spend your time in Lucerne. It's a beautiful city and there's lots to see (although you'll only have time for a brief walkabout). With more time, both cities are certainly worth a visit.