Guys, we're getting a little melodramatic about the Lexus here. Its not a Ferrari, its a large, easy to work on Japanese car. Anyone can work on a Lexus, nothing so special about it that it requires special expertise. Its not like a BMW, Mercedes, or VW in that fashion. Thats one of the great things about it, you're not tied to the dealer. Lexus techs are just that, techs. They're not "the best mechanics on earth" or anything. They just happen to be employed by Lexus. I mean, if we were replacing an engine or something that would be different, but its just a strut.
Take it to Midas. As long as they're doing Lexus parts, then whats the difference? Go for it. Their techs are trained on a wide variety of vehicles, including Toyotas/Lexuses. Just make sure they'll stand by their work like anyone should and you'll be 100% fine. I would probably hold the timing belt for someone more experienced also though. No reason they can't change spark plugs though.
Better yet like was said above, the thing for you to do is find a small shop that you can get to know the owners and such, then you'll get inexpensive, high quality repairs that you know are done right. I reccomend this to everyone.
I do want to give you some advice though. You really want to replace BOTH the struts on the same axle depending on the age of the car. Otherwise the handling dynamics of the car will be adversely affected and it could be a safety issue. Ask the shop what that would run you. Its like replacing one tire and not a pair. If I were you, I'd put some of those other items on hold and replace both the struts for safety.