With Lughnasadh/Lammas coming up here in the northern hemisphere, I thought it might be useful to talk about celebrating holidays in the NICU.
With our first child, we spent every major public holiday except Memorial Day, and every Wheel of the Year holiday except Beltane in the hospital. While the nursing staff decorated for mainstream holidays like Christmas and Valentine's Day, I wish we'd done more to celebrate our own holidays (at least when they didn't overlap some major crisis with our child).
When considering what we ought to do this time, decorations seemed easiest. Maybe a corn dolly for Lughnasadh? She'd go well on our little altar space - I haven't found one yet, but it's on my ever-present list. Or maybe a little sheaf of wheat? We can't have large amounts of food in the room, only snacks, so bread might be iffy, and that's a major staple for this holiday.
I went looking around online for other suggestions, and found a nice article at Parenting Children with Special Needs - its suggestions are applicable to many holidays, while most other articles I found were specific to Christmas (and a few mention Thanksgiving). Generally, the recommendations fall into categories like decorating your child's room and getting them special holiday outfits.
The other key thing in reading others' experiences, and in looking back on our own, is to do what feels right to you - celebrate how you want, where you want. Celebrate, or don't, based on how you feel. Change traditions or make new ones. Spend the day with family, or in the NICU, depending on what feels most comfortable. This issue of personal comfort and opinion is important - we had a large argument with family about not spending Christmas day with them while our son was in the NICU, because we felt it more important to be with him, rather than with the broader family, and they disagreed. Our decision, though, was that our child needed to come first.
Hopefully you only have one or two holidays to contend with - worst case, skipping a holiday or two because you're busy with your preemie won't kill you, and might just be less stressful than the alternatives.