While I thoroughly enjoy an IEM while travelling, especially when putting some Comply tips on the pairs I have, there is something nice about the full sound provided by an over ear/on ear pair.
For that reason I didn't want to include IEM's in this particular discussion, but I will look into the SE215s. They are priced rather competitively which makes them attractive.
To be honest, the SE215 isn't really "competitively" priced -- in fact, they're right around the price range where they should be, in my opinion. Some of Shure's higher-end IEMs don't have the bass you're looking for, but do have improved durability and better sound than the entry-level SE215.
The RHA T10i might also suit your preferences, since you're looking for a bassy but balanced pair. It doesn't have a removable cable, but it has a great cable and overall build nonetheless. It also happens to look pretty amazing, as well.
Why I'm recommending IEMs to you instead of headphones are because of my rather limited experience of them compared to IEMs, and also because I prefer IEMs over headphones because headphones often cause discomfort due to heat (which, in my area, is quite prevalent). If I were to recommend a headphone, I would probably suggest the Beyerdynamic DT1350. No, I haven't heard the headphone before, so I cannot make any judgements on sound, but what I can tell you is that they have a pretty great build and should hold up to the purpose you're using them for.
But now that you mention it, why don't you instead use the HD25? It has a more rugged build than the DT1350 and has the isolation you need. Also, they should be able to be stuffed in a bag. I hope you could elaborate on the specific purpose you're using them for so I could make better recommendations.
