Jan 7, 2016 - 1:22 PM
You can visit Mount Pilatus and Titlis in one day if the weather is fine and if you don't mind a long day. You could start with Mount Titlis, then back by train to Alpnachstad to take the cogwheel train up to Pilatus, and finally the cable car down to Lucerne.
Day 4 and 5 are very long too. Make sure to check all your trips in the timetable so you know what to expect in terms of traveling times. And, be flexible. September is a wonderful month on average, but if the peaks are in the clouds it's useless to go up there, so you need to do something else.
I'm not sure where you would stay all nights, except for the two nights in Lucerne. Take into account that moving from town to town and changing hotels takes a lot of time too.
If you switch day 5 & 6 so you end up in Zermatt, you can take the Glacier Express from there.
A Swiss Travel Pass will definitely be very useful with this amount of traveling.
I'd advice to study the links and especially check the timetable. My first impression is that it's too much for the number of days you have, but you if you don't mind hectic days it's all fine of course.