Here is another holiday favorite from "Meet Me in St. Louis."  It is lovely melody dominated by major 7th tonalities.  The song form is AABA, 32 bars, so it is relatively easy to navigate.
In this particular arraignment, there is an extended intro section as the band gradually establishes the groove.  And after 4 full choruses, there is a 4-bar vamp you can use to stretch out.

This song is rather unusual  Most popular songs from this era (mid 1950s) that were covered by singers like Perry Como, Robert Goulet and many others after that either originated in a movie, or was featured in one or more movies soon after hitting the Billboard charts.  This one is different in that there are really no notable movie connections.  It became popular on the strength of the composition and the artists that first recorded it.
The song is a straightforward ABA form, 16 bars in each section for a total of 48 bars.  The two A sections are virtually identical, so it is relatively easy to learn. This is a vessel that lends itself to improvisations that are free and flowing, or you can simply play a variation of the melody.