Warning:  Spoilers for Quest
For Glory 1-5!!

Elsa and Nawar

I can't talk about Katrina and Erana without discussing the ups and downs of
our favorite dancing girl and warrior woman.
In Dragon Fire our hero is able to get engaged to one (or more) women.
(Of course at this P.C. site we don't promote polygamy) ;)
Let's look at each person more closely:

Pros: Elsa is fiercely devoted to things, and you know she would definitely love you, admiring your heroic qualities, plus, you two will have adventuring in common!  You're both technically royalty, and you can rule Silmaria jointly.  As a thief, you can feel comfortable letting her know your secret since she is one, too.  If you're ever in a squeeze, Elsa would be there to lend a hand, or more likely a sword.
Pros: Nawar is very sexy and seductive, and you know you'll enjoy her...company.  She will probably be fun since she seems so interested in you, at least for a while... She is most likely a thief, so you can let her secret out to her if you're one, too.  Nawar knows how to get things that she wants.  If you marry her she'll get things you want as well.  Hey, if things don't work out between you two, there's always Budar!
Cons:  Elsa has a temper.  Elsa has a sword.  These things don't mix well (not for the hero, at least).  If you got married to Elsa one of you would be King of Silmaria.  Elsa might be resentful if she had to become Queen.  You might not agree with how she rules or vice versa. 
Special paladin note: One of you would become king, and since you are a paladin you'd most likely decline.  This means that you either go out adventuring (and leaving Elsa behind) or stay in Silmaria and feel guilty for not going adventuring.  Feelings are hurt both ways.
Cons:  I have the feeling that Nawar wouldn't be the most faithful of wives, though for some people that could be a pro.  Then you wouldn't have to feel guilty for cheating on her.  (And she wouldn't mind, either!)  We don't actually know too much about her from the games, but all she talks about is sex.  Is that all she knows?  Try having conversations like that for the rest of your life!  Also, what happens when Nawar's main charm (her beauty) wears away?  In general, Nawar doesn't seem to be the type to support adventuring.  She certainly wouldn't go with the hero, and she would want him back before night...

In my opinion, Elsa seems like a more suitable bride for the hero.  Nawar would only be semi-content with a thief: all other class types would be too strange for her and too different (the fighter less so).  Elsa is a good pick, but you have to think about her desire for power.  Either one of you will become king, but will that affect your relationship in the long run?
Remember, I'm biased for Katrina anyway so of course I would pick her other these two any day!  But that shouldn't affect your choice. *cough*  Really, it shouldn't.
With Katrina and Erana, some characters classes can't marry.  Elsa and Nawar will marry all characters classes, so never fear!  You can get to know these girls much earlier than Kat and Erana, and you can start courting all the sooner!  Strangely enough, Nawar's courtship is the most difficult, ironic for the woman who appears to "desire" you the most.  Could it be that she's using your affections for her own purposes? Nah!