JGram - The Japanese Grammar database http://www.jgram.org/pages/viewOne.php?tagE=invitation
We look forward to seeing you soon.
英文レター・メール （展示会への招待状） http://www.mamejiten.com/BE/sample/025.htm
It is a great pleasure to invite you for our opening ceremony.
We are pleased to invite you to attend our opening ceremony.
I'm looking forward to seeing you.
We believe that you will be delightfully surprised to@see some of our latest innovations in both concept and@design, and invite you to call for an appointment to visit our booth (#412). We will be@happy to arrange a demonstration time for you at your@convenience.