I have been a nurse for a little over a year. I first started on 5pm-5am (yeah ER has weird hours) and it killed me. After a shift re-bid I switched to 6pm-4am. I work 3 on 3 off and then 4 on 4 off and occasionally pick up shifts. 10s are a nice compromise between being at the hospital way too much and not feeling utterly exhausted every day.
I was in your same position back in June after I graduated from school. I worked as a nurse technician for 1 year on a med-tele floor and was immediately offered a position as an RN. I had to wait over a week to hear back about my ER interview but received an offer there. I thought about what I had seen working on the med-tele floor and ran the other way. For me choosing ER was the best possible thing I could have done. In less than 8 months I have seen more than I would have on med-tele in 5 years. I was scared out of my mind that I would kill a patient for the first 6 months. Just over the last month I feel like I am finding my groove and absolutely love it. If you enjoy an intellectually challenging and fast-paced environment ER is the way to go.