Why Delaware? Your own state's corporation laws are good enough unless you're already gigantic or going public, or already are in Delaware, or someone is specifically demanding it from you, which I strongly doubt. Plenty of gigantic, or public companies do not incorporate in Delaware. Why do you need to have a foreign-state incorporation rather than your own state? Make it simple and less expensive, and use local-state incorporation and local lawyers that are familiar with their own state's run-of the mill corporate laws. Delaware is not that special.
A Limited Liability Company form of entity can be simple to operate, but they are not flexible in having the ability to have multiple classes of investments by others.
If you're the only person, or one of several individual partners, and capital from other people is not a concern, then, sure, an LLC may work for you. Later on, if you have a partner-founder depart, and want to issue a different category of capital representation for him/her upon departure ("units" in LLC speak), you can't, so LLCs are not so good at transitions either. Creating a vesting process may also be cumbersome or not possible. Further, if you grow and need capital, you'll end up becoming a C corporation, to be able to have multiple classes of ownership shares.
C Corporations vs. S Corporations: these are elections that are made via a filing with the US Internal Revenue Service. The S Corp has limitations on what it may do and and still maintain its status as an S corp for tax purposes, instead of the default C corporation status.
If you are seeking investments or venture funding: VCs and investors prefer C corporations: the investor will not be taxed on net income as they would with an S Corp. The C corp. can issue convertible preferred stock, which is typical structure for a venture capital investment. S corporations can only issue one class of stock, so that also is typically a deal stopper for investors.
Venture Capital funders don't like LLCs or S Corporations for the above reasons, and will decline to participate, unless the entity converts to a C corporation.
It all boils down to, what are your likely financing structures, if any, and how likely will you later on need to become a C Corp. Be wary of subsequent entity conversion tax issues for owners and entities as well.
Here's a survey of only some of the issues: LLC, C corp. and S corp.
Choice of Entity - Startup Law Blog - Joe Wallin, Davis Wright Tremaine LLP (undated, but apparently 2012)
Also, benefits paid to employees through an LLC are fully taxable income to them, whereas with a Corp (either S or C) they are tax deductible (for employees owning less than 2% of the company).
Furthermore, the stock ownership ("units") situation with LLCs is awkward at best, like you said, so forget about incentive stock options and the like. I understand the simplicity and have used the LLC structure before for other reasons, but never for a multi-state entity.
Great input, thank you.
What are the tax issues upon dissolution/merger/conversion of entities from one to the other, for the owners and the entity itself?
Is there an impediment to rapidly converting a Subchapter-S corp into to C-corp - are there be any delays, fiscal year issues or alignments, or other IRS filing or election issues and impediments, again for the entity and for owners?
For foreign LLCs in terms of the "corporate veil" and limited liability, etc., set up in state Z, how does the foreign LLC get treated in other states of interest, states A, B, C, and D compared to the foreign corporation set up in state Z, operating in states A, B, C and D? Do those several states follow the IRS-election for taxation of local-state activity?
What advantages / disadvantages for the LLC to elect to file with the IRS the "filing as corporation" status, instead of the default sole proprietorship/partnership status, or --yes you can elect this too-- "Subchapter-S"?
Edit: After looking it up, benefits paid to employees receive the same tax benefits as other structures, BUT shareholders/partners are taxed individually on the benefits they actually receive. Non-ownership employees won't have the problem. But again, I am not a tax attorney or accountant.