Nicer thing to do would be to have the maintenance IP as your last A record. If the client can't reach your regular servers, it will automatically fall back to the maintenance IP.
That's not actually how A records work. Clients are supposed to randomly select one of the A records, although this doesn't always distribute the load as randomly as it should. (My company's site used to have 4 A records for 4 load balancers, and we found that one of them received 25-30% more traffic than the rest.) Clients certainly don't have a mechanism to retry if one of them fails -- they'll be stuck with the failing IP for the length of the TTL.
