Does it make a difference if the Hanukkah lights are lit for an hour or an hour and a half? Is it more of a 'Hiddur Mitzvah'?
The Mishna B'rura (672:6, citing Magein Avraham 672:3) writes:
If he put a lot of oil so that the flame will last longer, there is no mitzva in this. But with wax candles, there is a beautification of the mitzva when they are long. Nevertheless, one should not make them inordinately long.
The distinction between oil and wax is based on the Magein Avraham, who writes:
It appears to me that there is no beautification from changing the quantity of oil in oil lights. But with wax candles, when they are long they are more sightly... and I think that the Kol Bo wrote similarly.1
The Mishna B'rura (Sha'ar HaTziyun 672:9) infers a limit on preferred candle length from the שלטי הגיבורים on the מרדכי (Shabbos, fn. 2 on the beginning of Bameh Madlikin), who is in turn based on the Orchos Chayim (Hilchos Chanuka).2
Note that this is all based on the Mishna B'rura's stance on the modern day application of עד שתכלה רגל מן השוק (Shabbos 21b), which is a complex topic subject to various understandings by many rishonim and acharonim. If someone wished to be stringent and follow opinions that require a longer duration for the Chanuka lights,3 perhaps there would be basis for doing so.
Further, contrary to the Magein Avraham's view that there is no hiddur from more fuel, the M'iri (Shabbos 21b, "ומ"מ אם הוסיף מוסיפין לו") seems to suggest that there is a hiddur from using more fuel. This may suggest a dispute as to the nature of hiddur in Chanuka lights, with the M'iri taking the view that the duration of the flame is subject to beautification and the Magein Avraham maintaining that only the nature of the lights is subject to beautification.
1 From what I could find in the Kol Bo (§44) and Orchos Chayim (Hilchos Chanuka), the reason given for long candles is that Rabbeinu Shimshon required people to light long candles that could last as long as members of the household remain awake. He held that, by that era, the pirsumei nisa was essentially for the household ("ולשיעורא כתב רבי' שמשון שגם עכשיו כן והוה מצריך לעשות קנדי"לאש ארוכות"). If this is the source that the Magein Avraham was referring to, then the Magein Avraham's reasoning is different and novel.
2 I'm not certain how the Mishna B'rura derived a preferred limit on candle size from those sources. The שלטי הגיבורים mentions an approximate שיעור of oil that would suffice for 30 minutes plus of light, namely an eighth of a k'beitza. (As noted by the Magein Avraham, this quantity would naturally vary depending on the thickness of the wick). This is based on the Orchos Chayim cited above, who also mentions long candles as described in fn. 1. Perhaps, along the lines of the Magein Avraham's reasoning, the Mishna B'rura simply considered huge candles to be unsightly.
3 Possible reasons may include: 1. Uncertainty over whether you should light at sunset or nightfall. Rav Yosef Dov Soloveitchik reportedly used enough oil to last from sunset to around 30 minutes after nightfall for this reason. 2. Uncertainly regarding whether עד שתכלה רגל מן השוק is theoretically variable based on the reality of contemporary society. I heard from a disciple of the Rav that the Rav proposed this. 3. The possibility, per Rabbeinu Shimshon mentioned in fn. 1, that nowadays the primary pirsumei nisa is for the household and that the lights must remain lit as long as people at home are awake.
This is going to be unsourced untill I get around to it.
In modern societies where people are walking the streets till eleven o'clock or so, the time period of 'ad shetichla regel min hashuk' is extended.
This idea is mentioned by a few poskim both as a leniency to allow one to make a bracha when lighting later in the night and there is no-one else home. It is also mentioned as a lichatchila chumra, as in your case to put oil that will last long into the night.
This idea of taking other stringent opinions into consideration is called 'hiddur' by the Biur Halacha in hilchos lulav and esrog.