Hailey -
If the attributes for each of these features varies widely, then moving to a subtype model would be probably the best way to go. As Alan mentions, the FacilitySite subtype model is probably one I would emulate. Would it be possible for you to create a data dictionary (with Xray for ArcCatalog) or post an XML workspace document of the current street furniture features you have and attach it to this post? I'd like to take a look at the attributes you have for each feature and see if we should consider amending our model to accommodate a more complex set of features. We took a very simple approach initially and maybe we should consider evolving it in a subsequent release.
To your specific questions though; I don't think you need to reuse the TYPE field for the subtype designation. I would probably add a field called FCODE and use that for the subtype. Then you can reuse the TYPE field for the text domains that are specific to each feature type.
You could store some of the specific information in related tables (as Alan references below) but I might be a bit concerned the number of tables will grow as you add feature types.
If you don't mind sharing your current information model, I'd be glad to take a deeper look and provide more direction.
Scott