“Alternative” being to the ever-popular [name_m]Charles[/name_m]. I had a dream where I had a son named Charlie. This seemed like a good excuse to ask Berries a question :P.
I don’t mind if it’s a large stretch to get the nickname in or if the name is particularly obscure. [name_m]Just[/name_m] whatever comes to mind!
[name_m]How[/name_m] about using [name_u]Charlie[/name_u]? [name_m]Charles[/name_m] (a family name) is okay but I adore [name_u]Charlie[/name_u] so I have [name_u]Charlie[/name_u] on my short list.
Another vote for just [name_u]Charlie[/name_u]. [name_m]How[/name_m] about:
[name_m]Charlton[/name_m]
[name_u]Chase[/name_u]
[name_m]Chance[/name_m]
[name_m]Carl[/name_m]
[name_m]Carlton[/name_m]
[name_u]Chandler[/name_u]
[name_m]Charleston[/name_m]
[name_u]Carlisle[/name_u]
[name_m]Chasen[/name_m]
[name_u]Chauncey[/name_u]
[name_m]Chester[/name_m]
[name_m]Chuck[/name_m] (another nn idea as well)
[name_u]Chandler[/name_u]
[name_m]Chaplin[/name_m]
[name_u]Channing[/name_u]
I don’t love [name_u]Charlie[/name_u] as a stand alone. [name_m]Charleston[/name_m] came to mind first.
The easier choice would be to use a variation of [name_m]Charles[/name_m] in another language: [name_m]Carl[/name_m], [name_m]Karl[/name_m], [name_m]Carolus[/name_m], [name_m]Carlos[/name_m], [name_m]Carlo[/name_m], [name_m]Charlot[/name_m] (rhymes with [name_f]Margot[/name_f]), [name_m]Giancarlo[/name_m], Piercarlo, [name_u]Karel[/name_u], [name_u]Karol[/name_u], [name_m]Siarl[/name_m], Charlemagne (major GP for me!), Carloman…
another option is to go with similar-sounding surnames:
[name_u]Carlisle[/name_u]
[name_u]Carlyle[/name_u]
Charlesworth
Charleswood
Charlin
[name_f]Charlet[/name_f]
Charlick
Charlon
Charlson
Charnley
Charlier
Charsley
Charville
I would also suggest [name_m]Chaplin[/name_m], [name_u]Channing[/name_u], and [name_u]Chandler[/name_u], as previously suggested.
[name_u]Channing[/name_u] is my first favorite, followed by [name_m]Chaplin[/name_m], then [name_u]Chandler[/name_u].
[name_m]Charleston[/name_m] is my number one boys name at the moment. I vote that. 
Thanks guys! A lot of really cool names I hadn’t necessarily heard of or thought about before :).