I've been with State Farm for my personal insurance since I bought my Speedster in 2005, because of just what Mitch was talking about. SF allows me to use my speedster for whatever I want, as long as it's garaged and falls under the annual mileage limits. When I gave them my Speedster, I moved everything (daily drivers, houses, rental houses, etc.) over as well, for a package discount.
I've got big-boy liability ($500k) coverage on everything I drive, as well as a $1M personal (and business) liability umbrella. SF is not cheap, but I liked their lack of limitations. Their handling of claims however, gave me some pause - they've got something of a reputation in the business of cheaping out when the chips are down.
Several years ago (10 now?), I began switching lots of my insurance over to @Marty Grzynkowicz. It started with health insurance (I'm on the union plan now), but now he's my agent for anything business related - liability, work comp, and commercial vehicle insurance. He's been great at finding me good companies that provide solid value. We switched work-comp/business insurance this year and saved $5000.
I just got a quote from him for classic (and conventional) car insurance on the personal side with Safeco/Liberty Mutual. The coverage is great (there is a rider so you can actually use the classic cars) and the rates on the daily driver stuff are solid. The kicker for me is that will insure my limo with full coverage - as a personal vehicle on a commercial chassis Cadillac (something SF would not do). We're still nailing everything down, but I've been super-impressed.
My point is that these threads are useful beyond the usual "stated vs. agreed" value and Grundy vs. Hagerty discussion. With multiple vehicles being insured (and the attendant discount), the quoted rate from Safeco/Liberty was less than half the online quote I got from Hagerty for $65K of coverage on the Speedster, with higher liability limits and none of the restrictions baked into the Haggerty/Grundy cake.
Just throwing it out there.