Lucerne to Geneva by train - have you done it? Recommendations?

There is a direct train hourly on the hour, i.e., 8 AM, 9 AM, 10 AM, etc. with no changes. 3 hour trip. Look at the schedules on https://www.sbb.ch/en and note other options on that route involve changes. Managing your luggage depends on how much luggage you have. Hopefully you pack light with a roller bag and a daypack.

I've travelled that route and it's absolutely "doable". The trip is as short as 2H:53M with one or two transfers. The Swiss trains usually provide platform numbers, so transfers are very straightforward. Note that there are several stations in Geneva, and I used the main station when I checked that route.

Just buy your ticket at Lucerne station, board your train at the appointed time and enjoy the trip. Hopefully your luggage isn't too large or heavy, as you'll have to manage that on your own. There's usually a "bin"on the coaches to place larger items of luggage, and you can keep smaller items on the racks above your seats or the space between seats.

With a direct train every hour on the hour, no need to worry about transfers.

Looking at the amount of seniors I see on the train every day I would day that this is certainly doable. Swiss off all ages travel by train all the time. You will see.

You can save some money buying a supersaver ticket in advance. Such a ticket is however not flexible, so make sure you then take the train you selected during booking. With normal tickets you can take any train you want on the day.

Do you plan any other train travel in Switzerland? How are you getting to Luzern?

do you want the scenic train (Luzern - Interlaken - Spiez - Zweisimmen - Montreux - Geneva) which uses cogwheel and narrow gauge trains to get up close to the scenic bits, but is slow; or do you want fast (Luzern - Bern - Geneva) but lowland? Both routes are valid choices, but quite different...

You ask if we have done it. I have done both routes in their entirety but never all the way through in one go. I have done them in bits and pieces, as well as all the scenic railways in Switzerland over the years.

Another really key question - how much of the luggage you mention have you (will you) have?

I recommend a first class ticket as the first class cars are usually not crowded and there will be more room for your luggage.

Swiss trains are already expensive enough just in 2nd class. A full fare ticket is 80 CHF pp. Going to 1st class adds 60 CHF. The direct trains originate in Luzern. Arrive 15 minutes early and you will be one of the first people to board the train with ample room in the luggage racks by the door for large items.