Henrietta, There’s No One Better by Martine Murray.
This chapter book introduces us to Henrietta, future Queen of the Wide Wide Long Cool Coast of the Lost Socks.  Henrietta is a little girl with a huge personality and enormous imagination who invites readers right in to experience it for themselves.  Henrietta takes us to the Island of the Rietta filled with polka-dotted friendly creatures, introduces us to the problems of having a baby brother named Albert, and shows us the joy of saying really naughty words like Sheezamageeza!  This book is a joy to read aloud and has just enough potty humor and naughtiness to keep both boys and girls laughing along.  The illustrations are modern line drawings brightened with bright red touches.  They evoke the world of Henrietta even more vividly. 
Recommend this to teachers looking for a fun read-aloud chapter book for Kindergarten, first and second grade.  It could lead to discussions on imagination and creativity and maybe even having children create their own imaginary islands and creatures.  But this is one good enough to share with any child in your life and to recommend to chapter book readers themselves.