Where can I fit in seeing Lauterbrunnen in my itinerary?

It’s pretty difficult to get to Murren WITHOUT setting foot in Lauterbrunnen. Murren sits high above the Lauterbrunnen Valley, and you get there either by taking a lift plus train from Lauterbrunnen, or a combination of lifts from Stechelberg, a few miles up the valley from Lauterbrunnen. Lauterbrunnen itself isn’t so much a place you need to visit though. It’s beauty lies in its usefulness as a base to access the Jungfrau and Schilthorn areas. You can stroll through the whole town in less than a half hour.

You'll be traversing "through" and staring "at" Lauterbrunnen and the Lauterbrunnen Valley during your entire time in this area. You can't get to Murren without going through Lauterbrunnen (unless you have a helicopter).

As you go up in the cable car towards Mürren, or on the train towards Wengen you can look back down on Lauterbrunnen from above. When you are at the cable car landing in Gimmelwald you look back down the valley towards Lauterbrunnen.

You will see it from many different angles, even if you don't walk through it.

I've been going there for years and have never walked through Lauterbrunnen. Yet I've been all around, and through on bus and in car and never felt that I was missing anything.

Look up - not down.

We've walked through the town. In itself, its just another town. More shops and restaurants than Mürren. But it is the surrounding valley that is the attraction, and you'll already be seeing that. Its mentioned often because its a key transportation hub for the valley and a therefore a convenient base for visiting the valley.

On Day 1, take the gondola down from Gimmelwald to Stechelberg, then either take the PostBus or walk (about an hour) through the valley to Lauterbrunnen, passing the Stabbach Waterfall and have lunch in Lauterbrunnen. You can then take the gondola up to Grutschalp and the little train back to Muerren for a lovely round trip.