It sounds like you already have figured out a lot of ways to save money! And yes, your needs and preferences are likely to change with a baby as a traveling companion.

For hotels we do shop around for the best deal and always check the price offered when booking directly with the hotel. (We are finding the aggregator travel websites don't necessarily have the best prices any more.)

In terms of car rentals, we've consistently found renting through Costco to be the cheapest. But I imagine that might not be the case in all areas. But, they're worth checking into if you have a membership.

Also, I agree with the suggestion to consider less expensive destinations as well as to consider travel during times when your utilities are high at home.