Whenever I'm in a gym with limited poundage, I go for unilateral (single leg) deads and squats, using dumbbells. I also do bulgarian split squats instead (which I think is misnamed, as it really is more of a lunge movement). On a related tangent, Mike Boyle (a renoun hockey coach and strength coach that most strength coaches practically worship) has created some controversy recently by completely eliminating bilateral squats (2-leg, or the "normal" squats) for ALL of his athletes.
Anyway, a potential problem with regularly doing what you are doing is that you are never going heavy. Doing 20 reps of an exercise builds endurance, not strength. (And depending on many other factors, 20 reps may or may not stimulate hypertrophy – muscle size growth.) So if your goals are to get stronger or bigger, 20 rep-routines probably won't do it. Conversely, if you are just trying to add some endurance training to your non-running days, with running (an endurance activity) being your main goal, then you are fine with what you are doing.
For your wife, it all depends on her goals compared to her current condition. Keep in mind that it's nearly impossible for a woman to "bulk up". Think of how hard it is for us guys to bulk up – and we have all the right hormones to do so! Yet most of us still can't. Women, without those hormones, almost never bulk up – like 1 in 1000 who lift weights. So she shouldn't worry about that.
Generally, think of it like this:
strength – heavy weight for low reps (like 3 to 6); lots of rest in between sets
hypertrophy – medium weight for medium reps (like 8 to 12)
endurance – light weight for high reps (like 15 to 20); short rest in between sets
fat loss without muscle loss – mixed bag but I generally suggest mostly "endurance" type training but with even more intensity/bursts, yet with a week of "strength" type training every 3rd week or so; "undulating periodicity" is popular now but I'm not a fan because of it's complexity for the average person who doesn't have a personal trainer
Hopefully others will chime in here too!