Question: How might it be possible in Excel to convert a formula into an array formula, without using a hotkey?
Excel has a number of native formulas that allow you to create/ utilise arrays, for example
SUMPRODUCT()
INDEX()
OFFSET()
SUMIFS()
COUNTIFS()
AVERAGEIFS()
Knowing these native formulas well will allow you to avoid the CSE array formulas in most cases (if that is your aim)
For example, try this for numbered ranges:
=LEN(MAX(INDEX(C2:C14,,1)))
Furthermore, as a result of discussion below, this formula will work for all numbered and non numbered/mixed ranges:
=MAX(INDEX(LEN(C2:C14),,1))



That is taking the length of the maximum number, whereas the question is taking the longest length of the items in the list. Reversing it to
=max(len(index...
doesn't seem to produce the same result. Not criticizing, +1 – Raystafarian Sep 19 '14 at 15:08 
1Curiously, you could write the formula like this, though
=MAX(INDEX(LEN(C2:C14),,1))
this will address nonnumber lists – CallumDA Sep 19 '14 at 15:38 
1You should add that to the answer, that is pretty curious. And it works with nonnumbers AND mixed lists! – Raystafarian Sep 19 '14 at 15:41
One workaround for this limitation is to create a small VBA Sub, and assign it to a keyboard shortcut of your choice
This will convert the selected range into an array formula.
Sub ConvertToArrayFormula()
Dim rng As Range
Dim arr As Range
Set rng = Selection
For Each arr In rng.Areas
arr.FormulaArray = arr.Cells(1, 1).Formula
Next
End Sub

Good thought in general, but despite the title of my OP, I clarified my question in the post itself as "without using a hotkey?" Substituting one hotkey for another defeats the purpose. Now, if you can show me how to assign that Sub to a button on the toolbar  that is just the sort of thing I'm looking for! – David Michael Gregg Sep 20 '14 at 13:05

@MyPetOcean, was adjusting the formula not an option? You didn't explain why you need to be able to enter without using hotkey (I presume by "hotkey" you are talking about Ctrl+Shift+Enter) – CallumDA Sep 21 '14 at 11:37

I mean I'd like to avoid any hotkey. My initial rationale is longterm simplicity (and memorability) for nonsavvy users. But secondly, there just simply ought to be another way to do this. What other major software has important features only accessible via hotkey of all things? – David Michael Gregg Sep 21 '14 at 12:59
One answer is to develop your solutions using Names for both Ranges and Formulas.
Thus, the look of your formula may be improved by defining 'v' to refer to =C2:C14. The formula =MAX(LEN(v)) still needs to be array entered but, if you define 'n' to refer to =LEN(v), the array calculation is carried out as the default behaviour of a named formula. Therefore =MAX(n) works without using CSE entry.

1For people unfamiliar with using names ranges, it would be helpful to expand your answer a little to include a simple example of how to do it. – fixer1234 Apr 21 '15 at 20:00
=max(len)
specifically? – Raystafarian Sep 19 '14 at 11:41