I'm going to throw out a new idea: Weesen. It's on the lake and still quite central.

Flyhof, Weesen – Aktualisierte Preise für 2023 (booking.com)

For daytrips within the Canton of Glaris, it doesn't matter where you stay.
For daytrips in the greater area, up to Lake Zurich, Toggenburg, St. Gallen, Flumserberge, Liechtenstein, Klostertal, Montafon-Silvretta Hochalpenstrasse, Walsertal, Praettigau, Weisstannental, Chur, etc. it's better to stay between Schwanden and the transport hub Ziegelbrücke.
Walensee may have some fog in he morning

Thanks neckervd.

I think we've narrowed it down to Ruti or Linthal.

IMO Braundwald would be nicer, but the journey time for day trips would be 20 min longer (OW). The Braunwald funicular runs until midnight.
But of course, it's up to you,