Yeah, green are kind of insipid. Fine when you need the unripe vegetal flavors, which I do on occasion, but I much prefer the fuller, fruitier, peppery-er, flavor of ripe peppers.
Many jalapeño varieties have been created especially for the American market, i.e., hybridized to lessen the heat. You never know what you're getting. Though the fruitier, sweeter flavor can soften the heat a bit there are varieties that are better if you're looking for more heat. Try the early jal from
Seeds of Change or the Chile Grande from
Pepper Gal, among others, for next year.
If I have a lot I vac multiple bags for the freezer. I sometimes Ziploc a bag or two as well - those I use first. Vac bags can be cut, some peppers removed, then re-vac'd, but Ziploc'd peppers last for some time, though they can get frosty as Marc notes.