best Bavarian Alps town for easy walks/hikes

Garmisch-Partenkirchen is where I'd suggest. Still has the Olympic facilities for sports open to the public. Has the tram to the top of the Zugspitz. Has a nice hike to a couple of monasteries. Has the Casino. Has good bike trails. Has a really nice golf course. Is close to all the tourist places....

How long are you planning on, Rob? You will not see it all from one location.

Flat - look for towns or villages on rivers or lakes. Fussen is good heading west, Mittenwald on the bottom end. Oberammergau is in a nice valley, easy walk to Linderhof and Ettal, bus back. Bus to GP for the Partnach Gorge. Murnau, on the northern edge of the area, is pretty, has it's moors and is very little visited. Way east, which I would consider a different area, Ruhpolding is a good base.

I did a great two day hike up to the Zugspitze in Garmisch with my teenage kids. It was great.

Garmisch-Partenkirchen was what came to my mind as soon as I read your title. Many, many hiking opportunities and many lifts to help with some of the hiking.

Check out this site where members of the German Alpine Club (DAV) post activities. Its very easy to use and you can filter the hikes by all kinds of preferences.

I'll go against the grain here and not recommend GaP mainly because it's main claim is the proximity to outdoor activities but a lot of these are likely more extreme than what you are looking for. For "finding lots of nice, lower elevation walks and hikes, on the less strenuous side" I would recommend picking a town you find attractive as with the link above you can see there are many, many hikes from just about any town in the foothills. Towns on the Bayrische Oberlandbahn lines have good connections by rail with each other and good connections to the RVO network. If it were me I'd pick one of these.

If you are looking for something further from Munich than I'd recommend the Oberallgäu region. Oberstaufen and Oberdorf make good bases here.

DJ

Two suggestions "off the beaten path" (well, almost; on weekends there are many day trippers from Munich):

Tegernsee (or, more specific, Rottach-Egern at Lake Tegernsee).

(a) Hirschberg (ca 1700m but very good views); start in Scharling (accessible from the tegernsee by bus); (b) two lakes tour: from Lake Tegersee via the Gindelalmscheid mountain toe lake Schliersee (back to Tegernsee by train or bus); (c) take the cable car up to the Wallberg and hike down to the Tegernsee; (d) (very easy) take the bus to the Valepp forest station, hike up to lake Spitzingsee; take the cable car up to the Stümpfling and Rotkopf, and hike down to Lake Tegernsee or take the Suttenbahn cable car; (d) take the Bus to the "Winterstube" stop at the road towards Achensee, hike up to the pittoresque Königsalm (mountain hut that offers milk and butter bread); if you still have stamina, continue up to the Schildenstein (splendid view on the central alps, i.a. Großglockner and Großvenediger; have lunch at the Blaubergalm). (e) from the Valepp bus stop walk across the forests following the Valepp river to the Erzherzog-Johann-Klause in Tyrol (easy)

For more infos write to the tourism office in Tegernsee (https://www.tegernsee.com/en/)

Kochel

(a) tour around lake Kochelsee (flat, very easy); (b) from Urfeld at Lake Walchensee take the Herzogstandbahn cable car up to the Herzogstand and walk across the ridge over to the Heimgarten mountain (splendid view on lakes Kochelsee and Walchensee; alm hut on the Heimgarten), then back to the Walchensee.

More info: info@kochel.de and www.kochel.de

You can locate all places on the topographical maps of the Bayern Atlas.

I've found the Illertal of the Oberallgäu (near Oberstdorf) to be an excellent place to hike. There is an Austrian (not RVO) bus that runs from the Bahnhof in Oberstdorf all the way up the Kleinwalsertal (part of Austria) to Baad, with frequent stops at the small towns.

I know Germans who spend three weeks there every summer and hike in the valley. A lot of them ride the ski lifts up and hike down, although that is hard on the quads. We stopped at the TI office in the Kleinwalsertal (I believe it is in Hirschegg) and they had an excellent map showing hiking trails of all difficulties in the valley. We picked an easy one (no steep grades) and hiked 3.2 km from Mittelberg to Baad for lunch. If you don't want to hike back to Mittelberg, you can take the Walserbus back down from Baad.

There are also hiking paths in the Iller valley (Germany) down river from Oberstdorf. There is a very flat trail along the rail line down to Sonthofen (13 km) and probably beyond. You can hike down river to a village and ride the train (or bus) back or just hike as far as you want to and hike back.

One day I did a hike of about 5 miles from Fischen, where I was staying, across the river to the Schöllanger Bergkirche, high on the hill overlooking Fischen, then down into Schöllang for lunch, and back to Fischen.

We recently hiked in Berchtesgaden National Park. We took bus 846 from Berchtesgaden hbf to the terminus at Hintersee. From there, we hiked all the way to Hirschbicl (Austria). If you don't want to walk, there is almbus no 847 you can take from Hintersee that make stops along the hiking route. The trail goes up higher than Hirschbicl, but we stopped there and took the bus back.
The scenery is very pretty. The hikers we passed by were mostly German. It was an easy trip from Berchtesgaden by bus. Bus 847 is not free.

I should have mentioned this earlier:

Take a look at the DVV website. Google "German Volksmarch". If they have a walk anywhere near where you are going to be, when you're there, go and do it. The club sets out walks (marches) through local areas with an eye towards scenery and keeps the routes fairly simple. They have (usually) 5km and 10km routes. You pay a small fee, but get to walk a route well off the "tourist" path and they always have a beer hall with food at the end point. Usually there's a local band or two also.

You can easy do 5km in 2-3 hours. I was part of a crew that usually did 2-3 of these on a weekend. It's a lot of fun and I guarantee you'll see some fabulous country and meet some interesting people. It's also a good way to get tips from the locals, and there are a lot of military and expats who attend.

Highly recommended!

In Berchtesgaden, take bus RVO-846 (it's "free" if you have an RVO Tagesticket, a Bayern-Ticket, or a BGL TagesTicket Bus & Bahn) and go to Wimbachbrücke. From the bus stop, it's about a 1 km walk to the Wimmbachklamm (a narrow gorge cut by glacial melt water), then a 1 km hike through the Klamm, then about 2 km back to the bridge. If that's not a long enough hike, from the top of the Klamm, you can continue up all the way to the Watzmann, if you want to.

"lower elevation walks and hikes, on the less strenuous side." - where does ascending the Zugspitze fall into this category?