I used to work at a bike co-op in Atlanta and then helped found one at GA Tech, we did a lot of helping people fix up bikes. you get a lotta fun experience with a wide range of bikes, but what's fun is it's a very different experience than a bike mechanic. you're almost never working on bikes worth more than a few hundred, as those "good" bikes belong to people with money and they go to legit shops. We did get a few crazy super nice bikes too. But the fun stuff was old high-end bikes. things that were worth a lot and just sortof fell through the cracks, or shit would come in with garbage bikes that somehow accumulated top notch components. I personally developed a deep appreciation for the arabesque shimano 600's. so sexy and they work excellent.
Also really enjoyed the oddball shit - bikes with actual dual shocks, or shit old brands like huffy that got the trial components like positron shifters or whatever - garbage that never caught on for good reason but still interesting points in bike history. And we had some real cool scores come through, dedicated pursuit race or triathlon bikes, ultra early mountain bikes with the triangle bars, some first gen Peugeot aluminum frames bikes and early trek and other carbon tubes. Those first gens are always cool from the history, but they all had serious flaws - shit where there just wasn't the experience and time for testing to know the best way to affix a derailleur to an aluminum dropout or how to seal the ends of carbon tubes so they don't delaminate at the lugs
Those old electroformed shwinns came in pretty often, they're totally awful but in the same way kinda amazing with a real classic style.
I've had a lotta bikes from that, I definitely built a lot and rode them a while. Really enjoyed coaster brake single speeds: clean look, fun skids but can still coast downhill - built a lotta road bike coaster wheels for the fun. My goto has always been my old steel road bike. it's an early 80s Omni, a very short lived Japanese manufacturer I think used the same Nishiki builders. (NOT huffy Omni...)
It's a frankensteing of lotsa bikes, Italian and Japanese etc but it's always everything I want from it. I've won races and ridden thousands of miles commuting and whatever else. it's the longest I've owned any vehicle ever and my most trusted.
Still - I often say it and it's true - if someone offered me 300 I would sell it today. and sillier, if someone stole it I would 100% pay 300 to get it back lol. whatever. no one will offer me that and i'll forever love it