If trips really are limited to just a few each year, and a full-fledged annual membership to something like PPass does not appear to be very cost-effective, then perhaps it might be worthwhile to hunt around for coupons/passes for complimentary visits to a lounge(s), airline-affiliated lounges in particular.
Just beware of any entrance requirements such as having to fly on a paticular airline/within the network on or around the date of visit.
I have never made avail of "Coupon Connection" here at FT, but it may be worth checking out for something like this.