Never have your second profession started off as Mo/W, since the only Warrior skill you'd use(or should use) for farming is Bonetti's Defense. Mo/Me is a great choice, it's very versatile. My Monk is a Mo/Me. It's awesome for bonders, who rely on Blessed Signet for their energy. So Mantra of Inscriptions/Signets helps out there. Also there are several hex removal spells, energy stealing, and many other options available, especially through the Inspiration Magic line. So I strongly suggest it, you can always switch to Mo/W later.
A Necro/Mesmer is also an awesome choice, I have one. There are so many options open here, especially with all the hexes at your disposal. I don't know of it being "fragile," there are plenty self defense/healing spells. Vampiric Gaze, other life stealing blood spells, and then Distortion for Mesmer. Many "SS Necros" bring Sympathetic Visage along too, as it drains adjacent foes' energy when cast on an ally. Arcane Echo is also awesome, you can double up on SS(Spiteful Spirit). So Mesmer is an awesome choice for just about any profession, definitely give it a shot.
