Did I still get to vote for my local officials, (or run for election as one of those officials. Did I participate in government, at all?
What legal rights did I have that non-citizens lacked?
What obligations did I I have to the state?
Was being a citizen worth it? Was it something that people aspired to?
I can answer the question of imperial service and obligation in respect to Gaul in the period between 395 and 476. There first must be a distinct difference drawn between those who were involved in the civil, military and religious offices of the later Western Empire and the 'ordinary' Roman citizen. Make no mistake that it would be a narrow, aristocratic group of Roman elites who would serve in the imperial hierarchy, not the vast majority of Roman citizens. We must also acknowledge that by this time much of the population were Roman citizens; the Edict of Caracalla in 212AD had granted citizenship to all the free men of the Roman Empire. By the 4th century Roman citizenship had already lost much of it's exclusiveness and had become much more available.
During the 4th and into the 5th centuries for aristocrats in Roman Gaul, and indeed throughout the empire, a traditional civil or military career in the Roman state was something to aspire to. Imperial offices were highly coveted, and competition to fill them was often fierce. The expansion of Roman bureaucracy during the Dominate had created a political climate within which aristocratic status meant little without some imperial service that guaranteed an honorific title and a place of higher precedence in the Roman 'pecking order.' Participation in the imperial government could bring prestige, wealth (corruption was rampant in the later empire) and indeed a stable and long-lasting career. Roman citizens were not obligated to serve the state as imperial officials but this was heavily encouraged among the elites. Traditional Roman aristocratic culture required periods of negotium (service) and otium (leisure); aristocrats would hold office in urban areas or in the provinces, serve their term and then 'retire' to their villas for a period of leisure before seeking office once more.
The desire to be involved in the imperial government was for many a self-serving activity but not for all. Sidonius Apollinaris, a Gallo-Roman aristocrat who lived through the 430s to the 480s is indicative of a desire within a section of the Roman elite to see office holding as an obligation and to serve for the good of the empire. Sidonius praises his friend Gaudentius as winning distinction for his imperial service through well tested honesty rather that through 'a mother's rent roll, a grandfather's bounty, a wife's jewel or a father's capital.' He goes on to criticise his friend Syagrius for foregoing all ambition 'for the consular office' and 'to not bring slurs upon his nobility by spending too much time in the country.' Sidonius believed that to be a Roman citizen and a Gallo-Roman noble meant a duty to himself and the imperial hierarchy to serve in public office, but many of his peers did not feel the same. By the middle of the fifth century there was a deep level of inertia in Gaul as to holding imperial office, and Sidonius had to exert considerable effort to try and rally his peers to serve in an increasingly alienating imperial regime in Ravenna.
The concept of elections when referring to the later Western Empire is problematic; the Western Empire was not a democracy in any way. Direct elections had not been in practice in the West since the time of Augustus. These 'elections' were not what we would call elections today but rather appointments made by higher level officials on the basis of local power, reputation and the strength of the patronage network of the candidates. Ordinary Roman citizens would not have a say in who was appointed to local office; more often than not appointments were acquired on the basis of wealth, family ancestry and friendship connections (amicitia) as well as reputation. Sidonius is the perfect example of this in practice; he won the title of comes for composing a poem about the Emperor Majorian in 457, was appointed Urban Prefect of Rome in 467 or 468 on the basis of his learned reputation and family connections and was appointed to the bishopric of Clermont in 470 due to his local standing.
With regards to legal rights it is certainly true that Roman citizens *technically* held greater legal status than non-Romans but by the 5th century such distinctions in practice had begin to disappear. With the migrations of 406 and the prior settlement of 'barbarian' groups such as the Visigoths in Roman territory the lines between citizen and non-citizen became increasingly blurred. Being granted 'citizenship' of the Western Empire would have held little value for a non-Roman after 395 compared to one living in 100AD. Barbarians would, however, increasingly fill the official offices of the Roman military; the prospect of imperial office was certainly attractive to barbarian leaders who often wanted to be involved in Roman politics. Alaric, leader of the Visigoths between 395 and 410, made his career in the Roman Army and had aspirations of becoming a Roman general. Stilicho, a half-Vandal, rose to the rank of Magister Militum (Master of Soldiers) and served as regent for the underage Emperor Honorius which marked the highpoint of Germanic advancement in the service of Rome.
This is not to say that at the time contemporaries did not distinguish between Roman citizens and barbarians. Sidonius voices his displeasure at the Burgundians who 'reek of garlic and foul onions.' Attitudes such as these were far from uncommon in the Gallo-Roman elites, but the difference is that citizenship was seen more as a cultural issue than a legal or ethnic one as had been the case previously. Sidonius, when describing his contemporary Aborgast, refers to him as having 'drunk deep from the spring of Roman eloquence' and 'speaking the true Latin of the Tiber.' Aborgast was not legally a Roman citizen but was culturally Roman which was something Sidonius and others believed was the much greater thing to aspire to.