Recently someone googled into Baltimore Beer Guy searching for where to find these seasonal beers in Maryland. I try to be a resource, so here's what I know
1)I'm not a huge fan of these beers, so my interest/knowledge is a bit limited
2)As far as in bottles, I can guarantee almost any respectable bottle shop and beer/wine store will have several. They're particularly loaded at The Perfect Pour and I definitely recommend heading down their way to see what they have. Locally, Clipper City's MarzHon seasonal is widely available in bottles and occasionally on tap.
Also, be sure to check out my "Stock Up" listing of shops and custom-made map of places to find good beer in Maryland. I'm trying to build it so it's not the most comprehensive just yet. Both are on the menu at right.
3)More importantly, here's where I recommend finding them on tap.
Max's in Fell's Point is guaranteed to have some. They recently hosted a German beer fest and there are still a few leftover German beers and I'm fairly certain they've added more than a few seasonal taps.
Frisco Grille in Columbia had a ton on recently although the supply has dwindled a bit as they transition to their less seasonal selections.
Ellicott Mills Brewing Company in downtown Ellicott City should be a good option. The last time I was there (just a few days ago) they didn't have any "fest" beers, but they brew in the traditional German Alpenhof style and was told several seasonals were coming on board just as soon as a few of the other beers kicked. Everything is made in-house there and goes great with the fall season in general.
Also, you can find custom beers at various breweries. Flying Dog makes a Dogtoberfest Marzen and is likely on tap at their Frederick brewery (open on Saturdays from 1:30-4, they have a really fun tasting room). Dogfish Head's Alehouse in Gaithersburg also has their seasonal "Punkin" beer on tap right now. Ram's Head Tavern in Savage (and maybe other locations) should also have I think either an Oktoberfest or pumpkin or other "fest" styled beer on tap.
4)Other than that, I'd check with respected watering holes with at least 6-7 tap handles (Victoria Gastro Pub in Columbia and especially The Judge's Bench in downtown Ellicott City come to mind) to inquire what they have available.
5)Finally, I'd check with the handful of German restaurants in Maryland. I only know Eichenkranz (who I doubt carries any seasonals but you can ask) in downtown and Schmankerl Stube in Hagerstown which might, and if nothing else will have terrific German beers on tap.
Feel free to chime in with other suggestions or comments!
Update: Some updates ... Brewers Alley in Frederick has an Oktoberfest beer on tap right now. So too, does Dog Pub in Columbia. I've also stumbled across a third German dining establishment in Maryland that does have authentic German beers and should have some kind of seasonal on tap -- The Old Stein Inn in Edgewater near Annapolis.
12 Gauge AR-15
1 day ago