Display GPX in Google Maps or other simple application?
What you want to achieve is working perfectly fine e.g. with Locus Maps, as I can say from my own experience. You can even use KMZ files − and if they are self-contained (i.e. all pictures etc. are inside the file, no external resources linked), you can even create your own travel guides (I did that, works like a charm). The offline maps can be selected and downloaded for free from inside the app as well.