Aircraft insurance is generally "replacement value" insurance, and YOUR airplane should be insured for what YOU value it. Sometimes the underwriter or agent will say that "A Cessna 170 is not worth that much!".... to which you should be prepared to document for them WHY you believe your airplane is worth what you state.
Example: I purchased my airplane for $43K and insured it for $55K. The underwriter only wished to insure it for $40K (in 1999.) I disagreed and told him why. (It was an extensive restoration over 16 years to "new" condition, and very few Cessna 170B's are in "new" condition.) He wanted documentation to support my claim.
I provided him with copies of 337's which documented the extensive restoration and total replacement of all wireing, all hyd/fuel/air/vacuum lines, both metal and flexible, all cables, all pulleys, all windows, 80% of all sheet metal, new radios, new interior which was to certified standards, freshly-overhauled engine/prop/accy's, new exhaust, baffles and airbox, rebuilt wings, tail, and fuselage, new paint, and photographs and copies of the Oshkosh and Sun'N'Fun awards. I also asked him to locate ANY other Cessna 170 which he could find that had so much restoration that was
not valued at
more than my request. (I also reminded him that the base price for the current model comparable to the 170.....the 172.... is priced at $160K in similar condition.)
He admitted he could not find another 170 like mine worth less than what I wanted to insure mine for, and offered to insure it for up to $70K, (if I'd pay the appropriate premium.) I insured it for the amount I desired. Three years later he suggested, and I accepted his offer, to increase it's insured value.
YOU must decide how much you believe you will lose if your aircraft is destroyed. And keep this in mind...... when any damage adds up to about 70% of the value for which you insure it..... the underwriter will condemn it, take possession of it, and write you check.... and you have lost your pride and joy. Now...try to find another like it.
So: Insure it for what you think it will cost you to replace it and make the sadness go away.