Unfortunately as we age we begin to lose some muscle mass, usually beginning in our mid 50's. That is why weight training is important for seniors. I hate lifting weights also but feel I will have to do it for this reason. Yoga is for flexibility and core strength but doesn't really build muscle. My old age plan will be to probably give up running but continue cycling, as well as adding more weight lifting and yoga.

I find that in the yoga I take I seem to, or think I am, doing a lot with my body weight? balancing (one leg, arm balances, inversions) etc. but maybe not enough in itself.
But I just can't figure how to make weights fun. Any ideas? an bare bones minimum super quick workout ideas?

I think it depends on the yoga style you practice. I definitely gained muscle when I did ashtanga (sometimes called power yoga or vinyasa yoga). Not so much with hatha which I find to be too slow.

Weight training is necessary to help decrease muscle mass reduction that happen in us mature women. I like Yoga as well but per my personal trainer being overly flexible may not be ideal for a triathalete, (may lead to injury) so although I do attend a few Yoga classes I still weight train and don't go for maximal flexibility.

Mainly ashtanga...and some vinyasa flow/power.
and I dont really do many tris anymore, so maybe not a problem-but why is this a problem? and would 1-2x/week for 20-30 min be enough weights?

I use my own body weight for my strength training. I am not sure if the way that I do it is really strength training, but it has been working well for me so far. I first do 3 sessions of dips, push-ups, and sit-ups. I then go for a 3 mile run or a 1/2 hour bike ride at about 70%-80% maximum heart rate capacity. Afterwards, I finish with another 3 sessions of dips, pushups, and situps. The total number of the dips for the day would come to 50, also 50 for push-ups, and 100 for sit-ups.

I have been doing the above for a couple of months now, and today I did 2 pull-ups, so I think that these dips/pushups/situps have been working so far. I do find that a very strong abdomen is the bare requirement to be able to do dips or pushups. It has been my long-time goal to be able to just do a single pull-up. I have read somewhere that being able to do pull-ups mean that one is able to lift one's own body weight, if that is true, then being able to lift my own body weight for me is good enough.