[name_m]Nikolai[/name_m], [name_m]Silas[/name_m], [name_m]Alexei[/name_m], [name_u]Luca[/name_u] and [name_m]Matteo[/name_m] are among my favourite names. The middle names are less my style but all flow really well, and mostly work well in their combos.
The only one which strikes me as a slightly odd pairing is [name_m]Nikolai[/name_m] [name_u]Sawyer[/name_u]: one dashing, exotic twist on a classic and one modern/trendy surname name. Something like [name_m]Nikolai[/name_m] [name_m]Samson[/name_m] or [name_m]Nikolai[/name_m] [name_m]Oscar[/name_m] would work much better [name_f]IMO[/name_f].