Dead Rising 2 has coop, Dead Rising 1 does not. Have you played Nightmare mode yet? Nightmare mode is close to what DR1 and 2 play like normally. If you dislike how fast paced it is then you will not like DR1 and 2. DR3 has way more collectibles than DR1 or 2, but in 1 and 2 they are much harder to find (not listed on the map like in DR3).
I would say to pick up DR2: Off the Record. It's absolutely hilarious and you play as Frank as a re-imagining of the events of DR2. It has excellent co-op and there's even a free-roam called 'Sandbox' with challenges similar to the PP trials. Off the Record's story is better than 2's, in my opinion. It's funnier and a lot wittier and the characters just seem a lot more defined.
I slept in too late, now I have less time to do nothing.