This is an excellent suggestion! While ShippingEasy does offer the ability to preview different label formats (on the Label Settings page), we do not currently provide a preview of each individual label before you purchase them. If we were able to offer it in the future, where would you want to see an option to preview the label - on the Ready to Ship page after you've made selections?
In any case, I've forwarded your request to be able to preview all labels before purchase to our Product Team. We look forward to hearing back with more details on where you'd like to see this feature added. Feel free to provide more information on how you'd like to see it function, too! Thanks for your feedback!