I don’t know which one I like better…! Which one is more common? Are there any good Longer names for [name_u]Izzy[/name_u]/Izzie than [name_f]Isabelle[/name_f]/a? I don’t really like [name_f]Isabelle[/name_f]/a, but I like [name_u]Izzy[/name_u]/Izzie!
Isadora?
You could also use [name_u]Izzy[/name_u] as a nickname for a boy named [name_m]Isaac[/name_m] or [name_m]Ezekiel[/name_m]?
Isadora (seconding)
[name_f]Isolde[/name_f]
[name_f]Isabeau[/name_f]
[name_f]Ismay[/name_f]
[name_f]Isobel[/name_f]
I prefer [name_u]Izzy[/name_u] 
Isadora is my favourite [name_u]Izzy[/name_u] full name
I prefer [name_u]Izzy[/name_u]. I don’t know why but when I see [name_f]Izzie[/name_f] my brain wants to think it’s [name_f]Lizzie[/name_f]
Izzy, although I like the [name_u]Issy[/name_u] spelling more? I read a novel with an [name_f]Isidora[/name_f] nn [name_u]Issy[/name_u] in it once, and fell in love with [name_u]Issy[/name_u] as the spelling! I love the suggestion of [name_f]Isolde[/name_f]; I also love [name_u]Izzy[/name_u]/Issy as a nn for [name_f]Felicity[/name_f], or maybe even [name_f]Cecilia[/name_f], although I prefer Cici there.
I think [name_f]Ismay[/name_f] and [name_f]Isobel[/name_f] are great, too; what about:
Isisa (I think she’s a delightful name! Zulu name meaning “tenderness”.)
[name_f]Iris[/name_f]/Irisa
[name_f]Louisa[/name_f]/Louise/Eloise/Eloisa/Aloisa
[name_f]Sophia[/name_f] (as a huge stretch? I think [name_f]Sisi[/name_f] makes more sense than [name_u]Izzy[/name_u] though)
[name_f]Tirzah[/name_f]
Or maybe something with the initials “IZ”? Like [name_f]Iris[/name_f] [name_f]Zelda[/name_f], [name_f]Imogen[/name_f] [name_f]Zoe[/name_f], [name_f]Isla[/name_f] [name_f]Zuzanna[/name_f], [name_f]Ivy[/name_f] [name_f]Zenobia[/name_f], [name_f]Ilana[/name_f] [name_f]Zofia[/name_f], [name_f]Irene[/name_f] [name_f]Zinnia[/name_f], etc.?
Good luck!
Elizabeth
[name_f]El[/name_f]iza
[name_f]El[/name_f]izaveta
lizbet