Use a short outdoor loop as the baseline
Choose a circuit containing old-town lanes, a Reuss crossing and part of the lakefront. It introduces different sides of the city without assuming a long walk from the start. Chapel Bridge can provide orientation, but need not become the single image towards which the entire visit is directed.
In good weather, remain longer beside the water. In rain, shorten the loop and add one selected interior. Save a suitable nearby address rather than a general list of every museum in the region. A useful alternative fits both the geography and your interests.
Bridges, banks and older streets differ in surface and width. With a pushchair or limited mobility, investigate the specific crossings. A short route is not automatically step-free, and crowds can slow an otherwise straightforward connection.
Assess the lake beyond the sky alone
A boat trip depends on route, duration and return as well as weather. First choose whether you want a round trip or transport to another place. Then check actual departures. Boarding spontaneously without considering the way back can reshape the entire afternoon.
Low cloud limits distant mountain views. That does not make a lakeside stay pointless, but it changes the emphasis. If the panorama is your main reason for a longer sailing, keep the timing flexible where possible. A shore pause may provide the same desired change of pace during a short city visit without adding logistics.
A mountain excursion is another decision requiring its own weather and access checks. It should not automatically be considered a replacement for a wet city day. Conditions higher up differ from those beside the lake; a webcam or current official information can help you choose.
With an overnight stay, use a clear morning for the water and move an interior later. After a late arrival, a small town loop may be enough. Adaptation is easiest when only one activity is firmly booked and the remaining sections can exchange places without creating cancellation costs or an unnecessary rush.
