Usually the concerns regarding reservations or not are:
1. have a particular need and need to make sure it is met (e.g., dog breeds in an area known for breed bans, special amenities, etc.);
2. area that often books up months in advance;
3. holiday weekends/nights;
4. don't like flying by the seat of your pants, prefer a pre-established end to your travel days, have to ensure you're in a specific location at a specific date.
In your situation, I would say give your DH's way a try. If it works, then you've lost nothing and can relax more. If it doesn't work, then you go back to your planning ways and your DH stops complaining.