My notes....
Day 1
Yes, Suppenalp and Spielbodenalp are on the Northface Trail. Suppenalp has good lunch, but is very slow service, so take that into account on how long you want to spend there. Spielbodenalp is very simple, mostly drinks and some baked goods. If you want to stop for a beer, sure.
Alternatively, if you really are strong hikers, you might want to change up this day and just hike Birg > Grauseeli > Wasenegg Ridge > Bryndlii > Murren
This is a mix of the Northface and Rotstockhutte hikes and you’ll see basically no one on it because it’s only for strong hikers, with hiking poles for the scree — it takes the ridge right above Rotstockhutte, so technically has even better views, so you wouldn’t need to repeat Rotstockhutte
Day 2
If you take my advice above about switching to the Birg > Murren hike then I’d do this day…
Grutschalp > Allmendhubel > Suppenalp for lunch > and then 2 options from here:
1. Longer option Northface > Sprutz Waterfall > Gimmelwald (forested)
OR
2. Shorter option Blumental to Murren > Paved road to Gimmelwald
Dinner in Gimmelwald is nice (reservation fixed menu at the Pension or wood fired pizza at the Hostel)
Day 3
Schynige Platte Daube Oberberghorn Loucherhorn and back to SP + cog train up and back is probably a 3/4 day. You can make it more challenging by continuing the ridge and hiking to Faulhorn, Bachalpsee, Grindelwald First and then returning to Murren from there. That’s a long day and requires you leaving Murren early to make sure you don’t miss the last cable car down from First. Personally I’d probably just do the first option and then if you get back down to Wilderswil at a reasonable time and still want to do something, maybe walk the Lauterbrunnen Valley back to Stechelberg and ride the cable car up to Murren from there.
Day 4
Mannlichen to KS is going to feel like a toddler walk after everything else you’re doing :) To add to it —
Mannlichen > Royal Walk detour > Kleine Scheidegg > Fallbodensee + kneipp bath detour > Kleine Scheidegg lunch > hike to Wengernalp > optional hike all the way back to Wengen or train to Wengen from Wengernalp
Day 5
If you want to spend some time on one of the lakes, you could do this.
Wengen > train to Lauterbrunnen > train to Interlaken Ost > get on the boat to Brienz with your luggage and boat to Brienz > train to Luzern > afternoon in historic Luzern > train to Zurich Flughafen
I did really quick, rough numbers for this plan to help you with passes. They’re not exact numbers, but give you a close idea.
Full Fares = 520 chf
Half Fare Card only = 380 chf
Half Fare Card + Reduced Fare 6 day Berner Oberland Pass = 400 chf
Full Price 6 day Berner Oberland Pass = 400 chf
Half Fare Card + 4 Day Jungfrau Travel Pass = 430 chf
It looks to me like the 6 day Berner Oberland Pass is your best option. Having the half fare card is pretty much a wash, because the discount it gives you on the BO Pass + the portion of your travel to/from airport not included in the BO is just enough to break even, so probably not worth the hassle. If you get the 6 day BO Pass, all you’ll pay for is 2 tickets your whole trip - Zurich Flughafen > Bern on the way to Murren and Luzern > Zurich Flughafen on your way out (and Wengernalp to Wengen for 11 chf if you decide not to hike all the way back to Wengen on Day 4). The rest of the time, your pass will be your ticket.