I was surprised to find that Samuel & Samantha are currently ranked #25 & 29 in the US (for boys & girls, respectively, of course). Admittedly, they peaked 20-30 years ago, and have been dropping since, but still--30 years is decent staying power for a girls' name! Most don't stick around that long.
Of course, all this means that you probably know a Sam or two of either gender (or both), so finding new ways to get to spunky, solid Sam is understandable.
(note: I did start to delve into boy-Sam possibilities on a previous post, so if you feel a bit of déjà vu, you're not crazy)
Bassam (bah-SAHM, Arabic)--"smiling"
Isamu (ee-sah-moo, Japanese)--"courage"
Salman (SAL-mahn, Arabic)--"safe"
Samad (sam-AHD, Arabic)--"eternal"
Samang (sahm-ANG, Khmer)--"lucky"
Samay (sam-EYE, Khmer)--"daydream"
Sambor (SAM-bor, Polish)
Samir (sah-MEER, Arabic, Hindi)
Samson (SAM-son, English)--from Hebrew "sun". Another form is Sampson.
Samuli (SAH-moo-lee, Finnish)--form of Samuel
Stamatis (stah-MAH-tis, Greek)--another form is Stamatios.