What is the name of your state (only U.S. law)? Florida
Is it trademark infringement if I name my product La-Z-Bag and sell inflatable sleeping bags, a different products to LaZBoy that sell Home Furniture?
Trademark infringement centers on consumer confusion. If a consumer is likely to be confused as to the origin of a product or service by the use of the same or similar trademark, there is an equal likelihood that the new mark infringes on the old.
What a court looks at in an infringement suit is the strength of the senior user's mark - and, with La-Z-Boy the mark is a famous one making it a strong mark easily recognized by consumers. A court also looks at the similarity of the marks. La-Z-Bag is substantially similar to La-Z-Boy. The similarity of the product or service being offered is another factor a court will look at. Inflatable sleeping bags are similar to products offered by La-Z-Boy. The court looks at the intent of the junior user in choosing the mark - and it seems likely that you would not have chosen La-Z-Bag if it were not to trade on the reputation of La-Z-Boy. The court also looks at evidence of actual confusion in the marketplace. If in use consumers have been confused between your mark and the La-Z-Boy mark, that is infringement.
Your use of the similar mark could also lead to a dilution suit if the quality of your bags is not of the same quality as La-Z-Boy products. Your use of the similar name on an inferior product would harm the reputation of La-Z-Boy.
Finally, as Zigner noted, if you attempt to use the name La-Z-Bag, you are undoubtedly facing a costly challenge to your use by a team of experienced attorneys from La-Z-Boy and you are likely to lose the challenge.
I recommend you choose a different name that is unique to your sleeping bags alone. You can review all facts personally with a trademark attorney in your area but I suspect you will hear the same thing you are hearing here.
Good luck with your new product.