I would explore options for earning a return on any cash you know you will not need for at least 3 months. Vanguard Fund VMFXX, which is likely what your board member is suggesting, is a great option, depending on the size of the investment. Moving funds from your operating bank account to/from Vanguard may just require a phone call which is likely worth the return.

The suggestion of exploring an interest bearing savings options with the bank you hold your operating funds is also a great option, especially if you can move funds to/from accounts online. Again, depending on the size of the investment, giving up a 1% or so for ease of cash management online may be worth it.

In any case, idle cash should be drawing interest despite requiring a bit of adminstrative attention.