“Howliday Inn” (1982), a juvenile novel by James Howe, is a portmanteau of the word “howl” and the hotel chain “Holiday Inn.”
     
“Q. What is a werewolf’s favorite hotel? A. The Howl-a-day Inn!” is a riddle that was printed in The Gazette (Montreal, Quebec) on April 14, 1991. “Where do wolves stay when they travel?  In a Howl-iday Inn” was printed in The Little Giant Book of Riddles (1996) by Joseph Rosenbloom. “Where do werewolves stay when they’re on vacation? At the Howliday Inn!” was posted on Twitter by guadalupe_stein on September 15, 2009.
   
     
Wikipedia: Holiday Inn 
Holiday Inn is a British-owned American brand of hotels, and a subsidiary of InterContinental Hotels Group. Founded as a U.S. motel chain, it has grown to be one of the world’s largest hotel chains, with 1,173 active hotels and over 214,000 rentable rooms as of September 30, 2018. The hotel chain’s headquarters are in Denham, Buckinghamshire.
 
OCLC WorldCat record   
Howliday Inn. (Bunnicula series, #2.)
Author: James Howe
Publisher: New York : Avon, ©1982.
Series: Bunnicula series, 2.
Edition/Format:   Print book : Fiction : Juvenile audience : English
Summary:
While their family is away, Harold and Chester, a dog and a cat, are boarded at Chateau Bow-Wow where Chester becomes increasingly alarmed by the strange behavior of his fellow guests and the sudden disappearance of one of them.
 
Newspapers.com
14 April 1991, The Gazette (Montreal, Quebec), pg. C-10, col. 3:
Q. What is a werewolf’s favorite hotel?
A. The Howl-a-day Inn!
Roopak Singh
Age 8
 
Google Books
The Little Giant Book of Riddles
By Joseph Rosenbloom
New York, NY: Sterling Publishing Company, Inc.
1996
Pg. 120:
Where do wolves stay when they travel?
In a Howl-iday Inn.
 
Google Groups: alt.humor
Halloween Humor - 23
Craig Bennett
Oct 15, 1998, 3:00:00 AM
What hotel chain do all werewolves like to patronize?
Howliday Inn !
     
Google Groups: alt.tasteless.jokes
Werewolf Jokes
Mr Funny Bone International
Oct 30, 2001, 7:05:36 AM
(...)
What hotel chain do all werewolves like to patronise?
Howliday Inn !
 
Newspapers.com
3 February 2008, Los Angeles (CA) Times, “Jokes & Riddles,” pg. H2, col. 3:
What is a dog’s favorite hotel? Howliday Inn.
Davit, 11
Los Feliz Elementary
Los Angeles
     
Twitter
Alec Brownstein
@BrownsteinAlec
I wrote a joke for my 6 year old followers: Where did the werewolf stay when he went away on vacation?  The Howliday Inn
12:47 AM · Aug 3, 2009·Twitter Web Client
   
Twitter
guadalupe_stein
@guadalupe_stein
Where do werewolves stay when they’re on vacation? At the Howliday Inn!
10:58 AM · Sep 15, 2009·Twitter Web Client
 
Google Groups: trevs-daily-family-post
TREV- Jest For Kids 09-07-10
.(JavaScript must be enabled to view this email address)
Sep 7, 2010, 1:11:05 PM
(...)
What hotel does a wolf stay at?
The Howl-iday Inn!
       
Twitter
Cruise Select
@cruiseselect
Halloween joke!
Where do werewolves stay when they’re on holiday?
... At the Howl-iday Inn!
10:16 AM · Oct 10, 2012·Facebook
 
Google Books
Belly Laugh Hilarious School’s Out for Summer Jokes for Kids:
350 Hilarious Jokes
By Sky Pony Press
New York, NY: Skyhorse Publishing
2019
Pg. ?:
Where do werewolves stay on vacation?
At the Howl-iday Inn
 
Reddit—Dadjokes
Posted by u/FrankGrimesIV December 26, 2020
Where did the Werewolf stay when he went on vacation?
At the Howl-iday Inn.