Hi Mary -
Luzern is 1 hour and 2 minutes by train ( approx.) every 30 minutes. Trains at XX47 are direct. Trains at xx18 take 5 minutes longer and have a change at Zürich main station.
Depending on your type of flight ( how much time does it add to go through passport control if you are not coming from a Schengen country) or how much time is required at the airport before your departing, it is possible that you could eat by the riverside in Luzern, or walk around the old city for up to 2 hours.
(Let the pictures scroll through at that website and you'll see the outside view.)
That would require good luck on your timing- you'd have to catch the 1718 to Luzern (possible if you don't have passport control) or the 1747 (certain unless there is some kind of unusual delay) and come back on the 2035 from Luzern arriving ZFH at 2147.
If you returned on the 2010, with a change at Zürich, you'd be at ZFH at 2116.
The train station at the airport is very close to the arrival hall or to check in or outbound passport/boarding pass control. map attached. There is convenient luggage storage, but your baggage might be checked through.
The train service is extremely reliable.
I would not hesitate to do it myself, but I know the system.
I definitely would not recommend it to you unless you feel very comfortable about navigating the travel system. It would be an adventure. Definitely not with small children. All signs have English on them, along the route of this trip.
If not, the name Luzern is clear, and the times are in 24 hour clock format. On some signs you might see "Gleis" for "Track."
The only part that might give pause is a change in Zürich main station, but the signage is clear. It is just that some trains come and go from lower levels; the train to Luzern is always on the main platform. Signs will get you to the right track. Main track level is tracks 3- 18.
www.sbb.ch/content/dam /infrastruktur/trafima ge/bahnhofplaene/plan-zuerich-hb-plakat.pdf
All that said, Lucas' suggestions from Zürich are excellent. If you go downtown, there are many trains every hour, taking between 9 and 18 +/- minutes. The Bahnhofstrasse makes a pleasant stroll as far as Paradeplatz, ( about 15 minutes) where you should try to eat at the Zeughauskeller ( just off the plaza toward the river).
A walk along the river edge on the southwest bank starting at the Rudolf Brun Bridge (right by the Heimatwerk ( Handikrafts) store is really nice, and you can duck off at the Rathaus Bridge and cut over to the Zeughauskeller in 2 minutes.
This thread has some maps:
www.myswissalps.com/fo rum/topic/need-help-in-my-planning#cq6cUaDW9mqS6 v8AAFcRTQ
Scroll down to my post on November 10th in that thread.
I've also attached some pictures to this thread.
A useful map:
map.search.ch/?pos=683392,247115&z=51 2&poi=bergbahn,gebaeud e,haltestelle,parking, viasuisse,zug
Downtown Zürich would be a lot more relaxing than Luzern, but Luzern is a lot more scenic.
Two pictures from Luzern, both taken within 5 -8 minutes of the train station, are also attached.