I've done many rentals in cities for day rides - 90% good experiences just using the bike without bringing anything. That 1 time out of 10 is usually a slow leak in a tire that they didn't noticed when the last person checked the bike in. So, I always ask them to check tire pressure even for those short rentals.

I did the Seattle to Portland 2 day ride a few years ago and rented an aluminum Fuji road bike (my road bike at home is a carbon Trek Domane.) I brought my seat and shoes and Wahoo Elemnt, it came with SPD SL pedals. I had my bottom bracket to seat and seat to bars measurements with me and adjusted to match. I really couldn't tell that much difference in the feel of carbon vs. aluminum. That bike rental worked out great - the bike was even delivered to my hotel by a guy riding a bike pulling a trailer with my bike on it!