That is how we normally travel, we take weekend trips frequently (probably 6-10 a year) and every other year or so, we take a big trip. Maybe if you have money to burn you can afford to book two rooms, but we're not rich. Lol. I was the oldest of 3 kids and I don't remember ever waking up in the middle of the night on vacation when my brother and sister woke (I was 7 & 9 when they were born, so definitely old enough to remember), and in my own family, my oldest was 5 when the little one was born. We've never had a problem with the little one waking the entire family.
One parent waking up to tend to the baby is enough, the other can fall back asleep. And unless both parents are heavy sleepers, they will probably wake before the other child. Unless you have the two kids sharing a bed. Either co-sleep with the baby or put the pack n play as far from the older childs bed as possible. What does the 1 year old wake for? Are they still waking for a bottle? If your trip is far away, I'd try to wean them off before you go and just be done with bottles. If it's really close, then get the bottle as close to ready as possible before you go to bed (like prefill it with water and premeasure the powder, so all you need to do is dump and shake).